Cambridge Audio 851E / 851W Review

“So little distortion, it’s barely measureable”… “The best sounding amplifier Cambridge Audio has ever made” – That’s what Cambridge Audio say about their new 851E Preamplifier and 851W Power amplifier combination. Bold claims indeed, especially given the success Cambridge Audio have enjoyed with their recent flagship offerings.

It all started with the 840 series – the 840C upsampling CD player, and the 840A Class XD integrated amplifier that was, literally, in a class of its own. Then came the 840E/W – a pre and power amplifier that brought all the features of the 840A integrated, along with a few adaptations such as Cambridge Audio’s ‘terrapin’ impedance buffering modules and a refined version of the Class XD technology, and set the standard for a flexible, versatile, truly high-end hi-fi separates package.

Now it’s the turn of the new 851 series. The 851A integrated amplifier, the subject of a previous review, impressed me with its huge range of features, excellent build quality, and, most importantly, stunning sound quality. Now it’s the turn of the new 851E and 851W pre/power combination to take Centre stage.

Ordinarily, I’d give each component a separate review – however, in this case, I’ve decided to review the 851E/W (hereafter referred to as the ‘E/W’ to save the wear on my keyboard) as 1. Chances are, by the end of the review, you’ll have already bought them. (Spoiler alert – Yes, they really are that good).

The Packaging

The packaging is fairly standard for Cambridge Audio products – Both products are supplied in strong boxes (complete with corner protectors), with thick foam supports on either end of the product, and foam blocks protecting the front and rear. The off-set handles on either side of the box are present – this is a nice touch, and makes carrying these fairly weighty boxes much easier.

Inside each box, you’ll find 2 power cables (at least for the UK models) – a UK 3-pin cable and a European 2-pin cable. The 851W uses a special, high current power cable, while the 851E uses a standard IEC kettle lead.

In each box, you also get documentation, a control bus cable (more on that later), and, in the case of the 851E, the new Azur remote.


If I were to cover every feature of these components in this review, it would quickly become an audiophile ‘remaster’ of War and Peace. That being said, here are a few of the features on offer:

The 851W Power Amplifier

The first thing you’ll notice when lifting the 851W out of its box is the weight – to say its heavy is an understatement. It feels considerably heavier than the quoted 19KG – this is certainly not an amp you’re going to be moving unless absolutely necessary.

Take a look at the 851W’s feature list, though, and it’s not hard to see why. Not 1, but 2 toroidal transformers supply power to the unit – 1 substantial transformer drives the power amplifier stage, while another provides power for the input and other circuitry.

The 851W features 12 output transistors per channel, and, when using 1 851W in stereo mode, can output a total of 200W per channel (8O) or 350W per channel (4O). You can, however, configure the 851W amplifier to run as a monoblock power amplifier – allowing you to have 2 or more 851W’s in your system. When used in this way, the output power rises to 500W per channel (8O), or a massive 800W per channel (4O).

Cambridge’s ‘class XD amplifier circuit, designed to eliminate crossover distortion and combine the benefits of a class A amp with the efficiency of a class AB design, is the key to the 851w’s incredible sound quality. This clever technology takes a traditional class AB design, and adds voltage to shift distortion to a point where it is not audible to the human ear, effectively displacing it – hence the name ‘crossover displacement’.


CAP5, or ‘Cambridge Audio Protection 5, is a 5-way protection system that guards your amplifier and other equipment against electrical faults as well as operator error. It constantly monitors the internal components of the amplifier, to keep them working inside their safe operating zones. The 851W will automatically enter protection mode if:

  1. Positive DC voltage is detected at the speaker outputs, caused either by an internal fault or by hard clipping of the amplifier.
  2. Over-Temperature Detection – Monitors the temperature of the output devices, and keeps the temperature of the within the limits specified by the output device manufacturer.
  3. Overcurrent Protection – Stops you driving the amplifier too hard, or with speakers of 2 low an impedance.
  4. Short-circuit Protection – Checks that the speaker terminals are not shorted together. This can be due to loose wires, or spade connectors that are too large for the terminals.
  5. Intelligent Clipping Detection – Detects when the amplifier is clipping or overdriving its output.

CAP5 insures your system is guarded against any internal fault, or case of ‘operator error’, that may occur – with the price of these components, this is invaluable. Catching these faults can save you a lot of money in the long run.

The 851E Preamplifier

Where do we start – Firstly, the specs. The 851E preamplifier boasts THD figures of <0.0045% THD and a signal to noise ratio of <90 DBU – as Cambridge Audio rightly say, “In preamplifiers, that’s a very good thing!”

The 851E features no less than 8 inputs – the first 3 of which being switchable between balanced and unbalanced, and the 8th a recording monitor loop – for use with 3 head analogue cassette decks, open reel machines or computer sound cards.

Single-ended RCA and balanced XLR preamp outputs are provided, as well as a mono subwoofer output with optional 200HZ low-pass filter.

A solid state volume control offers precise linear volume adjustment reserving the purity of the audio signal, and retains perfect channel balance even at low levels – something that is often difficult to achieve with standard analogue potentiometers.

Bypassable tone controls are fitted, allowing you to tailor the sound to your preferences, to compensate for deficiencies in your room acoustics or your speakers. For those audiophiles who dislike tone controls, it’s possible to disable them with the press of a button – they’re switched in and out with a relay, so when disabled will have no effect on the sound. The 851E also remembers whether or not the tone controls are enabled for each input – meaning you can have them automatically enable for the tuner, but not the CD player – this is a nice touch.

Both units also feature control bus connections, allowing them to control, and be controlled by, other Cambridge Audio equipment. Trigger inputs and outputs are provided, and the 851E also has an RS-232C port for use in custom installations.

Build quality

Both components feature Cambridge’s acoustically damped, all metal chassis. These solid, well-damped chassis not only look good, but provide a solid platform for the sensitive electronic components which are susceptible to vibration, as well as RF and electro-magnetic interference. They both feature thick, brushed aluminium front panels, and have matching grilles on the top.

Both units feel extremely solid and well put together – there’s no flex in the casings when you lift them, and they’re reassuringly heavy. Tapping on the top of each unit yields a dull ‘thump’, unlike the metallic ringing made by other, less well build components. The sides of the 851w do have a resonating ring to them however – this is hardly surprising, as there’s very little space on the side due to the numerous holes for ventilation that cover the sides, top, and bottom for airflow. These are required as due to the nature of the class XD technology, the unit becomes hot in operation. It is essential that these components be installed in a location with plenty of airflow – such as an open rack. They may become too hot if installed in a cabinet – and why would you want to hide them anyway?

Initial impressions

Initial Setup

As you would expect with a pre/power combo, the initial setup is somewhat more involved than with a standard integrated amplifier. Fortunately though, Cambridge include a handy quick-start guide to help you get things up and running. It’s fairly simple though – and if you do connect something in the wrong place, Cambridge’s ‘CAP5’ protection system will kick in and save the units before any damage occurs.

851W: The front

The front of the 851W is refreshingly simple – a single power button, and a number of status lights, are all that adorn the thick, brushed aluminium facade. The lights are used to show the status of the amplifier, as well as allow you to access the hidden configuration menu. It’s clean and simple, as you would expect.

851W: The back

Here’s where things get interesting – the back of the 851W features a multitude of input/output connections and switches, allowing you to tailor it to your needs. Balanced XLR and unbalanced RCA inputs are provided for each channel, as well as loop outputs for both to connect further 851W’s if you wish to use more than 1.

Switches to switch between stereo and mono, balanced or unbalanced, and bridge mono/bi-amp are provided, as well as a massive, solid power switch and the AC power connection.

The unit features solid speaker terminals that can accept bare wire, or, by removing the caps in the ends, banana plugs. Rounding out the connections are the control bus and trigger in and out connections.

851E: the front

As you would expect, there’s a lot more going on on the front of the 851E preamplifier – despite this, however, Cambridge Audio have kept the clean, simple layout that is consistent across all of their devices. Positioned vertically either side of the central display are the input selection buttons – it’s nice to see direct access buttons for each input rather than a click wheel. Inputs are switched by relays – meaning there’s little, if any, crosstalk between inputs as is common with cheaper, chip-based input switching devices.

On the left, you’ll find power, the headphone jack, and the mode button used to turn the volume to a balance control, and to access the main configuration menu. On the right, you’ll find the tone controls (which, when pressed, protrude from the front allowing you to turn them – a further press hides them). There’s the direct button for those audiophiles who think tone controls are the root of all evil, and the volume control.

The volume control feels slightly cheap and wobbly – this is probably due to the digital encoder pot Cambridge Audio used – It would’ve been nice to see a better, higher quality encoder used in the 851E. Also, the gap between the knob and the front panel isn’t equal all the way round – again, a better quality encoder would probably solve this. The control however, turns very smoothly, gliding along as the volume is gently raised or lowered.

851e: the back

The back panel of the 851e can seem daunting at first – there’s a lot going on here. Firstly, we have the IEC power connection along with a power switch. Balanced XLR, and unbalanced RCA preamp outputs are provided, as well as the mono subwoofer pre-out.

Next we have the inputs; 8 of them in total, 3 with both balanced XLR and unbalanced RCA connections, the remaining 5 RCA only. Input number 8 is a recording monitor loop – and, as such, is accompanied by a line level output. It would’ve been nice to see 2 recording loops, for those of us who wish to connect, for example, both a sound card and a cassette deck.

Finally; there’s 2 3.5MM trigger input/outputs, an RS-232C port and the Cambridge Audio Control Bus connections.

The terminals and connectors on both units are solid and individually supported with screws – so there’s no chance of breaking them with a tight plug. The XLR terminals on the units aren’t too happy accepting my Audioquest Red River cables – they’re very tight, and the latches don’t work properly. However, these use non-standard XLR plugs – so other cables would probably work fine.

The remote

As long time readers will know, I love the Cambridge Audio remotes – and this one is no exception. The remote supplied with the Azur 851E can control all of the 851 components, as well as the stream magic 6.

It feels nice in the hand – it has just the right amount of weight, and balances perfectly when you’re changing the volume or using the central navigation circle. The central circle of buttons, including the volume, skip and navigation control, produce a gentle click when pressed which is a very nice touch. The buttons are slightly raised where necessary, making key controls such as volume and skip easy to find, even when you’re lost in the music.

I purchased an 851C CD player along with these components, and was somewhat disappointed to find it is still being supplied with the old Azur remote. I like having a spare remote – therefore it would be nice to see the entire Azur 851 line shipping with the new remote – for consistency, if nothing else.


The E/W components have several features designed to enable you to integrate them into everything from a simple home AV setup, to an advanced custom installation environment. Trigger in/outputs allow you to control the components from any other device with the appropriate trigger connections, such as an AV receiver, media centre PC, and even some remote controlled power strips.

The Azur remote control can be used to generate commands such as power on/off and mute, for use with learning remotes. Holding down the respective buttons for 12 seconds generates an IR code that can be used to program other remotes. If you choose to use the RS-232C port, there’s a set of remote control codes available from Cambridge Audio’s website.

Both units also feature the Cambridge Audio control bus, allowing you to integrate them into a full Cambridge Audio system. The control bus allows you to, for example, power sync components, or control the volume on your 851E preamp from your phone/tablet using the Stream Magic 6.

Connecting one of the supplied control bus cables between the E and W components allows the 851W to be brought in and out of standby along with the 851E preamp. It would be nice if, when connecting headphones, the amp was automatically powered off – and if headphones were connected from the start, it were not powered on. This would save causing unnecessary wear on the components of the amp – there’s little reason to have the amp powered on when using headphones. There doesn’t appear to be an option for this, though I’m sure it could be addressed in a software update.

There’s not much info on the control bus – the diagrams and instructions provided in the user manuals are vague and don’t go into enough detail – making it hard to get the system working the way the user wants. It would be nice to see a detailed control bus guide that clearly outlines all its functions and how to use them. I’ve written to Cambridge customer care regarding this, and will update this article when I receive their response.


Both the 851E and 851W have on-board configuration menus – the 851E’s is accessed using the front panel display, while the 851W’s uses the status lights to relay information to the user. As you would expect, the 851W has very few settings that can be changed – many of its settings are changed using the switches on the rear of the unit.

The 851E preamp, however, has several settings that can be altered. These include settings for the control bus and the various trigger outputs, the auto power down (APD) which causes the 851 components to enter standby after a period of inactivity, and the ability to change the volume display from DB to arbitrary volume units (0-90).

You also have the ability to name each input individually – enabling you to change the input names to correspond to the connected devices. For example, “CD Player”, “Streamer”, “Tuner” etc.

The 851E’s menu system is easy to use – however, there’s an extremely short delay that makes using the system frustrating. Upon calling up the menu by holding either the mode button or 1 of the input select buttons, after a few seconds of no interaction, the unit will return to its normal display mode. This is extremely annoying, as it gives you hardly any time to alter the settings; especially if you’re referring to the manual for directions.


Usage is as simple as it gets – with the E/W connected together with a control bus cable, powering up the 851E will cause the 851W to power up also – after a series of rhythmic relay clicks from both components, they’re ready for use. I have a soft spot for any component that clatters to life with a series of relays – and these components are certainly no exception.

Selecting your source is as simple as pressing the desired input select button on the front panel or the remote. The 8th source is a recording monitor loop – pressing input number 8 will activate that input, pressing it again will return you to the input you were listening to previously. This is useful if you have a 3 head analogue cassette deck, or are recording using your computer’s sound card.

The sound

Most importantly, how do they sound? Well… Musical, powerful… stunning.

The first thing that’s immediately apparent when you first listen to the E/W combination is the lack of noise. Not musical noise, but the noise floor that is so apparent with many other systems. It’s like removing the protective film from a components display; or the difference in sound between a full range speaker and a 2-way design with a crossover, the elements of the track being brought to the forefront of the sound stage with precision and startling realism.

The 851W has an unparalleled ability to convey the musical nuances in a performance. It’s got power in reserve to cater for those hard-hitting, chest-pounding drum kits or orchestral swings. But, at the same time, it has a softer, warmer, more emotional nature that makes music, well, music. The weeping lament of a violin or woodwind instrument. The subtle nuances of the piano. And, of course, the expressiveness of the human voice. All the elements of music that stir the human soul, beautifully rendered and presented to the listener like an intricate piece of art.

Of course, some credit must be given to the 851E – which shares many of the 851w’s characteristics; mainly The low signal to noise ratio and THD figures that result in a noise floor that is, to the human ear, virtually non-existent. The result? An incredibly clear, natural sound.

A system is only as good as the source components connected to it – therefore, it is essential you choose source components with characteristics that match those of the 851E/W – Cambridge’s own 851C and 851D, in particular, being the obvious choices. In my system, I use an 851C and a stream magic 6 – with everything connected together using balanced XLR connections. 1 851W was used – due to budget constraints; I was unable to obtain a second for my system. This is certainly a plan for the future – the audiophile in me is begging to hear these in a dual mono configuration.

The first thing I immediately noticed was how good these components sounded out of the box. Usually, especially with higher end components, they require a week or so to break in – allowing the properties of the electronics inside to settle down and reach optimum performance. Sure, given time these components get better (the optimal break-in time is around a week) – but never before has a component sounded so good in its first hours on my kit rack. A positive start – and it gets better.

We start with some Nirvana – and the ‘MTV Unplugged in New York’ album. ‘Where Did You Sleep Last Night?’, a favourite among some reviewers, sounds every bit as good as I was hoping. The track starts with a hard-hitting guitar intro – it’s not overdriven, rather the classic ‘American Clean’ sound. The track builds from what is otherwise a gentle start to a powerful screaming crescendo, full to bursting with emotion.

This is a track that brings most lesser systems crashing to their knees in a puddle of distortion, bright highs and musical mess. The 851, however, rises to the challenge, presenting a beautiful wide-open sound stage, with each element of the song meticulously arranged – all amassing to an incredible performance.

There’s no hint of brightness or harshness in Cobain’s powerful vocal – and there’s no lack of punch either, the music slamming into your chest at full force.

In fact, the entire album sounds phenomenal – the E/W accurately not only accurately conveyed the music, but also the room acoustics – this is, of course, in part due to the quality of the recording – but it’s impressive none the less.

Next to something softer, and another favourite amongst reviewers. Norah Jones’s ‘come away with me’ is as gentle and enveloping as you could hope for. The bass line is spot on, the 851W showing its ability to grab hold and keep control of those bass drivers. Again, the sound stage is wide open – and the performance is brimming with detail.

Many systems compromise ultimate detail retrieval with power or smoothness – however, with the E/W (and with most other Cambridge Audio equipment for that matter) this is simply not the case. In fact, you’ll be amazed just how much detail these components can bring to your attention. It’s not that the details didn’t previously exist – the 851 adds nothing to the music that wasn’t there already. It’s just bringing them to the forefront, and separating things out – so rather than blurring into one another they get their own space to breathe. This is particular evident in orchestral music – or songs that have orchestral parts.

Play ‘Whisper’ by Evanescence – a piece from the metal genre, but with stunning production and a sublime orchestral ending. Every instrument stands out – not in an obtrusive way (they still blend), but you can hear, and focus on, every single one. It’s the same with the vocalists – The feeling that they’re standing in front of you, within an arm’s reach is simply beautiful to behold.

It’s not just the amount of detail these components retrieve – it’s ability to convey subtle nuances is equally impressive. The velocity with which a drum is hit… the resonance of a tom, or size of a snare drum. The movement of a vocalist’s mouth, or the slightly deadened sound caused by a misplaced finger on a guitar string. All are startling realistic – just as they would be in real life.

Linkin Park’s ‘Hands Held High’ from the minutes to midnight album further demonstrates the virtues of the 851 components – it’s a simple rap/spoken word track, with an underlying bass line and simple snare/hi-hat rhythm throughout. It demonstrates the 851’s timing/rhythmic abilities, and its ability to keep control of the those bass drivers – with each note starting and stopping perfectly in time. It’s not lacking in rhythm or excitement – instead, its sense of rhythm is more refined, making the urge to reach for the volume and start the party even more irresistible.

You can add an excellent headphone stage to the merits of the 851E preamp too – while it’s obviously not going to compete with high-end dedicated headphone amps, it sounds much better than it has any right too at this price.

In fact, I’d happily put it up against many mid-range headphone amps. It’s got plenty of power, driving every headphone I tested with ease – and it takes nothing away from the sound of the 851E. In fact, using headphones proves just how low the 851E’s noise floor really is; yes it may be possible to measure it, but I challenge any human to hear it

The final test tracks are taken from the newly released ‘Going to Hell’ album by The Pretty Reckless. ‘Sweet things (Acoustic’, an acoustic version of ‘sweet things’ found on the deluxe pre-order edition of this album,, is a perfect example of what a talented band can create when computers, special effects, and Auto Tune are taken out of the equation. Of course, the 851 E/W renders this track perfectly (did you expect any different?), but it’s particularly impressive using headphones.

Again, reverb (and perhaps room acoustics) are fairly prominent, and the single acoustic guitar has tons of attack. It’s played hard too – especially in the choruses.

The detail, both in Taylor and Ben’s vocals and the 16th note accents on the hi-hat during the verses, is all present and accounted for – the system simply does nothing wrong; and that’s all you can possibly ask for.

Finally, to ‘heaven knows’ – a fun, upbeat track with a backbeat similar to queen’s legendary ‘we will rock you’. The first thing you’ll undoubtedly notice is the triple knock after the first couple bars – it jumps out at you, just as it should. After all – it’s designed to silence the crowd, who join Taylor Momsen in the choruses. The 851 series keeps it together, even when things become more complicated – it’s one of those songs that demonstrates the 851’s ’bring it on’ approach to music.


I normally struggle to summarize reviews – however, in the case of the 851E/W, it’s simple. Buy it, and thank me later. Chances are you’re already raising a phone to your ear and calling your local dealer for a demo – if that’s the case, this review has served its purpose. If not, I suggest you do so now… if anything, you owe it to your music collection.

The performance of this system is truly staggering. The potential for an 851 system with more than 1 851W is equally staggering – if you can afford it, do it.

Is there anything you would add?

Yes, a couple things. Firstly, a second (or even 3rd) recording loop – it would be nice to be able to hook up a cassette deck or 2, as well as my computer’s audio interface. I’d also like to see the digital volume encoder upgraded to match the build quality of the rest of the preamp.

That annoyingly short delay in the 851E’s menu system needs to be dealt with, and I’d like to see the ability to prevent the 851W automatically powering up if I have headphones connected. And finally; I’d like to see a better, more in-depth control bus manual.

But compared to the extensive list of pros (stunning sound, tons of features, amazing build quality, excellent headphone stage, and – did I mention – stunning sound), these are very minor things that could be altered with a software update, or minor hardware changes.

In summary; another stunning set of components from Cambridge Audio. Pair the 851E/W with an 851C or 851D and some decent speakers, and I’ll see you in musical heaven.

By Ashley

I founded Audio Appraisal a few years ago and continue to regularly update it with fresh content. An avid vinyl collector and coffee addict, I can often be found at a workbench tinkering with a faulty electronic device, tweaking a turntable to extract the last bit of detail from those tiny grooves in the plastic stuff, or relaxing in front of the hi-fi with a good album. A musician, occasional producer and sound engineer, other hobbies include software programming, web development, long walks and occasional DIY. Follow @ashleycox2


  1. Hi there!
    Im from sweden and wonder if the new edge w poweramp is so much better than 851w?
    I have the smaller 651w togethet with 851n.
    Sound really good with my new quad z3 speakers.
    But the z3 can be a tad bright when i raise the volume. Feels like the 651w maybe has its limit?
    But new edge has the same power as mine so maybe the 851w would fit better? The edge is probably a much more refined amplifier than 851w and would fit the lean and bright sounding z3s better? I mean half the power of the 851w but still much more to buy.

    I heard alot of people on forums who have had problems with the 851w. They go hot and somtimes one of the channels doesnt work.
    Probably alot o heat stresses the components inside. Maybe the edge is more reliable?

    So 851w or edge w?

    Best regards Peter

  2. Hi Ashley, many thanks for your detailed reviews. As we know, 851e is now discontinued. Is 851a the replacement? I know one is preamp and the other an amp, but from the user point of view, what are the differences? My 851e is having some trouble and I will be taking it back to Richer Sound for possible repair. Since I am a bit OCD and have to have a plan B in place, should the problem be not solvable, can I replace it with 851a and still get the same results? Thanks so much in advance for your input.

    1. The 851A can be used as a preamp, but it’s not as high quality as the 851E is and doesn’t have balanced outputs. The 851E has significantly lower distortion and a much better volume control. In terms of user interface and features they are mostly the same, with the 851E having an extra balanced input. Can I ask what’s wrong with the 851E? If it’s the volume control it’s a relatively easy fix and happens on the 851A and previous 840 series as well. but I’ve known RS and Cambridge recommend the wrong part be replaced on more than 1 occasion, often leading to a unit being declared irreparable when in fact it isn’t.

      1. Hi Ashley, many thanks for your reply. In fact I posted a question back in 2016 asking for your advice. I ended up buying 851n, 851e and two 851w (bridge mono) and a CA CXU cd/blu ray player. My record player is a P3 and I use Tannoy XT 8F. All was good until around November last year when we started having the RCD in our fuse box to trigger off. This was intermittent and we couldn’t really find the cause. We had electrician called in numerous times and all the circuits and the fuse box are good. Their advise was to disconnect one appliance at a time to find the problem. This was a very lengthy process because like I said this was an intermittent phenomenon. Ultimately we have now narrowed it down to the 851e and since it has been unplugged we haven’t experienced RCD triggering off.
        Now I use the 851n as preamp although I have to say I don’t think it is anywhere near the 851e. Additionally we cannot use the record player since 851n has no analog input.
        I think I may have to send the 851e for a check but deep inside I am hesitant to do so, since I hear mixed messages about the quality of repair by CA and the fact that 851e is discontinued and I cannot buy a new one, in worst case scenario.
        It is a real shame they have discontinued the 851e! I am wondering why did they do that and why haven’t they introduced a matching substitute?
        Thanks again Ashley and sorry for the very lengthy post!!

        1. I think the 851E was discontinued due to lack of sales. They were heavily promoting use of the 851E with an 851N as soon or 851D as soon as they were introduced, and so it seems as though the typical CA customer has no need of an analogue preamplifier. It’s. great shame as it is really a rather good unit.

          The issue to which I was referring with the volume control is one where the grease in the digital encoder on the front panel melts, causing contact problems and causing the volume to ramp up on its own. I’ve fixed many an 851A and 851E with this issue, which was usually incorrectly diagnosed to a bad volume controller chip, or the volume relays in the case of the 851A. This issue affects many manufacturers, not just Cambridge but theirs seem to be some of the worst for some reason.

          That is an odd issue however with the 851E triggering the fuse box. I would start by checking the power cable and checking the fuse in the power cable’s plug. Otherwise a repair would be your only option, it’s difficult to suggest what might be the issue without diagnosing it further. It could be as simple as a loose ground or a bad connection on one of the boards, or a fault in one of the circuits causing it to draw excessive current or an earth leakage. Out of interest was it tripping the fuse board when it was powered up only, or did it also happen when the 851E was in standby?

          Have you also checked the wall outlet, and power strip (if you’re using one) that the 851E is connected too? Something as simple as a loose earth screw will cause a modern RCD to trip.

          As for a replacement preamplifier, I think using an 851A as a replacement would actually give you worse performance than the 851N. For an analogue preamp you’d have to look outside of CA unfortunately.

          1. Thanks so much for your reply Ashley.
            I guess I can understand from the business point of view why they have stopped the 851e production, but I honestly hope I don’t have to look for a preamp in a different brand!

            Yes this problem also occurs when the unit is on standby! I use a third party power cable from Chord Company. But I will definitely take your advice and use it’s original power cable and see how it goes. I will let you know the outcome.

            Thanks again Ashley and I hope you have a nice weekend.

            1. Would definitely try the original power cable and fuse. I can’t tell you how many of these so called ‘audiophile’ power cables I’ve seen which either had a daft design flaw which would cause a modern RCD to trip, or were so poorly made that a failure would result in the same outcome.

  3. I am having the following system setup:
    DALI Rubicon 6.
    Mission Cyrus 2.
    Cambridge Audio 851N streamer.
    Cambridge Audio CXC CD transport.
    Rega Planar 3 with Elys 2.

    Shortlisting amplifier to upgrade:
    1. Cambridge Audio 851W
    2. Roksan Caspian M2 power amplifier or Blak.
    3. Emotiva XPA.

    Turntable playback via:
    1. MS2 integrated amplifier with speaker cable switch.

    Should I get Rega Fono MM? Would there be significant improvement sound quality output?

    Or should I get new integrated amplifier? How’s sound quality compare to power amplifier configuration?
    Which one better:
    1. CA 851A?
    2. Roksan Caspian M2 integrated amplifier?
    3. Roksan Blak significantly better than M2 integrated amplifier?

    I read many website but unable to ascertain which is better. Seek your expert advise. Thanks.

    1. My Cyrus 2 with PSX power bank.
      Speaker cable: Chord Clearway.
      Interconnection cable: Chord Clearway.

      I prefer clear, balance, true to original mid and treble (sound and vocal), with solid tight bass.

      Listen to pop, indie, and sometime symphony orchestra pieces.

    2. I wouldn’t use two amps with a speaker select switch. If you wanted to go down the power amp route, I would buy a good analogue to digital converter and use the CA streamer as the preamp. Alternatively I would opt for an integrated amp as you suggest. From your shortlist I would choose the 851A, but I would also look at high end Marantz for a similar sound signature to what you have now or high end Yamaha, both of which give you an excellent internal phono stage.

  4. Great review.
    I have the 851N and 851A, but a fault with the A I have swapped for a W. PAired up with some Monitor Audio Gold300s it is sounding absolutely biblical. Though I think my neighbor doesn’t approve.

    Is there any wayyou’ve found to dampen the bass slightly through the floor? without hampering the sound?

    Thanks again for a great in depth review

    1. Thanks, great system! Are you using floor spikes with your speakers? If not I’d highly recommend that you do. You could also try putting a slab of granite or similar beneath the speaker which used in conjunction with the spikes may help to reduce excess bass slightly. Out of curiosity what was the fault with the 851A?

  5. well i have had no problems with my 851e or my 2 851w i have had them for 2 years now i changed my speakers from bose to paradigm S8 and added a dbx 3bx it made a big differens and if you run them hard you should have a fan on each amp.they run cooler and it will prolong the life of your amps

  6. Hi Ashley,
    Do you remember how was the low end of the 851 W? Does it compare with the old krell Amps?
    Is there any comparison with HEGEL H20?
    Any other recommendation in the 200 w?

  7. 851 W with the CXN will sound better than CXA and CXN?
    Will someone hear any improvement on the sound that will justify the double price?
    I know they sound different and the 851W is more powerful.
    Since you have both you should know.

    1. Yes, it will sound better, whether the improvement is worth double the price only you can decide. That is determined by your system, your hearing and your music. If it were my money I’d go for it. Unfortunately I don’t have them sat here to tell you, the 851W was reviewed a long time ago and the CXN review sample was returned at the beginning of the year.

  8. Good review, I have an 851E and 851W on loan from my dealer. After one night of listening, they ain’t going back! Never heard my ProAc D38s so alive. Next trick: get hold of a second demo W 🙂

    1. Excellent, glad you’re enjoying. I’d be interested to hear your thoughts when you add a second 851W. Out of interest which source components are you using?

      1. Andy,
        You started saying something that is interesting. 2x851Ws and 851N and b&w PM1…. In my case i would like to see how they will perform with the 805 s and how they are connected

        1. Hi I have had them running as mono bridged and mono bi amped. Latter configuration in my opinion is significantly more open in the soundstage and my chosen choice. Unfortunately I have had 2 amp faiIlures so have just swapped them out for two Roksan Caspian M2 power amps which also shine. Soundstage of the Caspians is much more 3d. Andy

            1. Hi they stopped producing any sound at all and the cap 5 protection kept flashing 4 lights indicating a short. I went through 3 amps before giving up. I wonder whether I was just unlucky and got some from the same faulty batch as not generally seen any issues indicated elsewhere. But at this price they need to be more reliable. Shame because I think they are superb. Caspians I have to say are equally good but probably just win on overall musicality. Do you have a view on the Caspians. If so would be interesting to hear. Andy

              1. The first black unit I received had the same fault. According to our local importer there was a manufacturing batch fault. I made sure to get a replacement from a newer batch which has been good so far (a couple of weeks).

              2. Interesting and a real shame. I like the Caspian amps, though I’d probably still favour the Cambridge as it sounds more class A-like. The CA amps do take a long time to run in and reach their full potential.

                1. Any alternatives to the 851W?
                  Anybody heard or or opinions for

                  PEACHTREE AUDIO NOVA 220SE
                  Parasound Halo A21
                  Benchmark AHB2 Power Amplifier
                  Odyssey Khartago
                  Parasound Halo A21
                  Rogue Audio Stereo 90
                  Emotiva XPA

                  Not many reviews for power amps

                  1. Ashley. Yes they do sound different. The Caspians if anything are a little warmer. I be interested in your comment re 851w’s sounding more like class As. Why do you think that? Andy

                    1. They have a certain crisp, clear sound to them which is very class A-like. They’re also free of any audible distortion that I can detect, no matter how hard they’re pushed. IMO they sound a bit rough until they run in, but they’re very nice amps once they get going. They just have an effortless quality to their sound which IMO makes them a joy to listen to. I’m not really sure how to describe it beyond that.

  9. Azur 851N & Azur 851W …….. why someone will need anything else than this.
    What is everybody is talking about.
    Azur 851N is a stunner as a pre amp. Read some reviews please and have an audition if you can.
    Tidal, Spotify, PC or MAG USB 2, Ethernet, Network-attached storage (NAS)… input for CD transport….What else someone can ask.
    I have CXN CXA 80 combination and B&W 685 S2s and the sound is fantastic for the money. I am upgrading to Azur 851N & Azur 851W combination that will bring the music in another llevel. What Is dificult to decide .. is a good pair of speakers that will do justice to the upgrade.
    Any suggestions?

  10. I have purchased an 851D along with a 851W. I was using an M DAC directly with a Roksan Kandy K2 power amplifier. This gave a pretty good sound along with my Focal 962 speakers. However the pre amp in the M DAC is not very refined , and caused clipping at higher volume levels.. So I opted for the pair… 851D and matching 851W.
    However, setting them up over Christmas I was disappointed to say the least. I have a new Cambridge CXC and Cyrus CD transport and listening to classical music cds . At -90db nothing happened of course but turning up the volume did nothing at first to improve matters. At “half volume ” at about -40db I heard what sounded like an old transistor radio : a tiny sound in the distance. I carried on and it was obvious that the volume knob needed to be set very high to get a reasonable sound. In fact -20db was suitable if I sat right in front of the speakers. But if I wanted some clout as you would with friends around then -10db was needed. For getting a sound similar to an old amp at 40 x 40 watts then full volume was needed and clipping occurred. I checked and tested everything with a multi tester. No problems found. QED XT 40 speaker cable used. It seems to me that there is very little gain from the built in preamp on the 851D. I have very good hearing , but often I like to hear some of the quieter parts with classical music. I also like rock ( Dire Straits, Eric Clapton and country music Dixie Chicks, Nanci Griffiths ) Dire Straits need some welly as does Clapton soul guitar. This set up is not for me ; so weak and nowhere like the massive sound you talk about, apart from distortion. Is this likely to be a fault or would the 851E give more clout used with a stand alone DAC , I have an M DAC with a linear power supply (superb ) , but the in built preamp is not up to much. I hear the 851E output is about 8 x 8 volts, would this correct the problem.
    I am disabled and spend a lot of time in bed, hence I cannot get to a listening room .. Another subject which needs attention, what happened to HiFi Answers magazine : and a chance for many shops to make a killing lending machines, but not in Leamington Spa. No Richer Sounds ! Very strange, we need one. Does anyone loan Cambridge Audio equipment ?
    Anyway , could you or anyone help me as I don`t know who to talk to ; so many so called HiFi staff have little real knowledge if I ring for support. Around here it is all very high cost or Currys. Both useless in my case.
    Many thanks. Mit Street.

    1. Very strange. I think there’s definitely a fault somewhere, as that doesn’t sound normal at all. Have you checked that your 851W is configured properly in stereo mode and that your speakers are connected properly? I assume you’re not bi-wiring? Using the 851E as a preamp, the 851W had no problems rocking out and i never took it anywhere near full volume. I can’t seem to find an output rating for the 851D.

      1. Thanks Ashley, I have checked all the connections and settings. I can only assume that either the 851D is not working as it should, the gain might be wrongly set , or I have to accept that the two just strain to create a decent volume due to poorly designed pairing by Cambridge. What I have done is order an 851E with an 8 x 8 volt output and then feed this with either the original 851D or better probably an existing M DAC with linear power supply. Trouble is, all this costs big money and people like myself with disabilities ( I am bedridden nearly all the time ), find such expenses beyond them. I have tried to contact Cambridge Audio, but after leaving a message , nobody bothered to get back to me.
        I hope Cambridge read this , it might just give them a reminder of who pays their wages.

        1. Mit John Street, you say that you have checked all connections and settings. Do notise that the volume can be set and tuned for every input at least that the case for my 851E&W combo purchased in Denmark. I have only had this set for af few weeks, so I have not read every single detail of the manuals yet. But I am quite sure, that it could have something to do with you volume issue.
          In any case, I am very happy with the Cambridge machinery, and have found it very convincing so far. Thanks for a great review, Ashley.

    2. John,
      Even thogh it always take ages to get a reply from Cambridge,
      Speak with Troy (Cambridge Audio)
      He is very helpful.
      Regarding Reliability of CA products, I am sure they could be better but there you go.
      If you want a Tank … go for
      Bryston’s , Mark Levinson, Parasound Products.

      Regards APAPAS

      1. It doesn’t matter what you go for, every company has their fair share of faulty components. It only takes one electronic component to go bad, rendering the piece of equipment faulty. I’ve had worse luck with gear made in the UK than I have with some of the mass-produced kit coming out of japan and China. Buy whatever sounds good to you and is within your budget, and if it goes wrong providing it’s in the warranty period it’s down to the dealer or manufacturer to sort it out.

  11. i have the 851 e and 2 851 w with bose 901 ser. 6 sp. a minx 301 sub with the dac magic 100 i dont care what anyone says when you crank it shit happens

  12. Hi Ashley do you have any comments on the 651W power amp? My budget can’t quite stretch to the 851W. I am wandering if they have similar characteristics. I’m trying to also establish what brands of speaker might be a good match for the 651W

    1. The 651W is a very good amp. It’s not going to compete with the 851W – the 851 has more power, better control, and of course the class XD technology. The 851 is cleaner and more open. That said, the 651W may be adequate depending on your usage, and the only way to tell for sure is to hear one.

      As for speakers, I generally pair my Cambridge gear with Tannoys. However, the beauty of the Cambridge gear is that it’s so neutral in its sound that it’ll get the best from almost any speakers – even (in the case of the 851W at least), speakers which are known to be difficult to drive. In fact, I’d be tempted to opt for lower sensitivity speakers, just to utilise some of its power.

      1. Thanks for prompt response Ashley. I was thinking about Focal (Aria 906 or 816 VW) or the Tannoy Precision 6.2 (if I can get them – seem to be sold out everywhere). Not sure if I will need to go with floor standers or whether the bass on the 906‘s will be sufficient. The listening room is about 25 SQM and has a lot of glass

        1. It is a very bad move to order audio components amps especially speakers (unless they can be returned) without an audition preferably at home ,I do not care for Tannoys nor do I like any Cambridge component

          1. In most cases I’d agree with you; but sometimes auditioning simply isn’t practical. Why do you dislike Tannoy and Cambridge components out of interest?

          1. I heard the Tannoy Cambridge combo and did not find the SQ natural, just not worth listening to. As for Cambridge my long experience of the brand is that IMO they are total rubbish every Cambridge item I have purchased had to be returned for a refund and some of the designs are just simply ugh.

  13. Commencing from the 7Os when original Cambridge Audio was founded up to a few years ago from Richer Sounds every Cambridge Audio product I purchased was returned due to QC problems.

    1. Personally I’ve had a few issues, but Richer Sounds customer service was fantastic in every instance. I’ve had the same number of issues with ‘high-end’ products as I have with Cambridge gear.

  14. I would like to know whether Cambridge Azur 851 C / E and Azur 851 W is better than QUAD Platinum DMP Pre & Platinum Stereo Power Amp. Pl advice.


    1. Whether or not it is "better" comes down to personal opinion. I've never heard the amps you mention – so can't comment on them. My advice would be to take a trip to your local dealer and hear the Cambridge setup for yourself, or ask your dealer if they offer home demos.

    2. Its a waste of time asking any reviewer if one amp sounds better than another, you have to listen for yourself preferably at Home as for Quad under its present ownership this another brand like Cambridge that does not interest me.

  15. I would like to know whether cambridge 851 C / E and 851 W  is better than QUAD Platinum DMP & Stereo Power Amp. 


  16. Great review! Thanks!

    Looking to buy the 851W paired with the 851D. What could be the BEST way to enjoy my APPLE LOSSLESS librairy with the 851D?

    BLUETOOTH or my MACBOOK connected via USB…? Keeping my MACBOOK by the AMP in the leaving room… not that sexy…

    What would you do? Advices?

    1. That would be a great system. While bluetooth is great, if you want the best sound quality a direct connection is the way to go. I'd connect your mac directly via USB, and make sure to set the 851D to USB Audio 2.0 mode (details in the manual) as this will result in better sound, and is supported natively by Mac OS X.

  17. Thanks for the review!

    I got the 851W+C and asking myself to get the 851E or not.

    Im not sure if the 851E will surpass the 851C Pre Amp?

    What do you think?


    1. Hmm… the reason for me getting the 851E was because I have a lot of sources, some analogue (including a turntable and cassette deck) so digital inputs were enough. The 851E will give you a physical volume control, and a headphone jack which is always nice…

      I believe the preamp in the 851C is entirely digital – and therefore has as little affect on the sound as possible. Providing you don't need analogue inputs, I don't think adding an 851E would benefit you; if you want the physical volume control, and headphone amp, not to mention extra connectivity and bluetooth, look at the Cambridge 851D DAC/Preamp.

      1. Thanks for your message.

        I dont need any analog inputs and the physical volume control and a headphone jack would be nice, but I can live without it.

        I just thought maybe I would benefit from the analog pre amp from the 851E over the digital 851C.

        I cant find any photo showing inside the 851E.


        Besides I love to have a sleek system only with the 851W+C.

        I guess I will need to demo the 851E.


        1. Your best bet would, as you say, be to have a demo. I would take a photo of mine; however opening it will void the warranty. 🙂

          If you don't need the analogue inputs but want the volume control and/or headphone jack, I'd go with the 851D; That offers you a lot of flexibility. Of course, if it's just the headphone jack you want, you could look at an external headphone amp, such as the rega ear.

          1. Thanks! Please dont void the warranty for me 😉

            Just sad cambridge shows no picture inside the 851E.

            And thanks for the hint to Rega Ear.

          2. Hi Ashley,

            there is just one thing I dont like about my 851W+C, it's the LED's.

            They are very different in brightness, on the C very bright and on the W I would say have the brightness. That looks a bit poor.

            Do you see these brightness differences too, or I'm hthe one with badluck?


          3. I think the LED issue is just by design… try changing the display brightness settings and see if that helps at all. If not, maybe speak to Cambridge. I've not noticed any such problems with mine.

          4. Thanks for your reply.

            Changing the display brightness will not change the LED brightness.

            Cambridge is aware and knew this problem already but can do anything to solve the problem.

          5. AH, OK. That's somewhat annoying; you'd have thought the leds would change with the display. At least they're aware of the problem – though they should've been aware of, and fixed it during testing.

            I can't really think of anything to solve it, other than covering the leds with something – which isn't helpful when you may need to see them. Hopefully Cambridge will release an 851C V2 and fix the transport, as well as reducing the led brightness.

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