Arcam are a company well known for their class leading amplifiers. They’ve been building them since the company was founded in 1976 when their first product, the now classic A60, established Arcam’s reputation thanks to its sleek looks and exceptional sound. Debuted at the Munich High End show, the rHead headphone amplifier is the latest product to mark Arcam’s 40th anniversary and join their extensive product range. The product of Arcam co-founder and legendary amplifier designer John Dawson, the rHead is a no compromise discrete class A headphone amplifier building upon the impressive headphone stages found inside its integrated amplifier stablemates.
The rHead is designed to work with just about any headphone, from high-performance over ear models to tiny, highly efficient balanced armature earbuds. Unlike typical loudspeakers, the impedance and sensitivity varies widely between headphone models, from 600 ohms (requiring a higher voltage to achieve a given volume) down to 16 ohms or less and up to 30dB for a given voltage input. A well-designed headphone amplifier must have low residual noise levels when using sensitive headphones (a problem evidenced by the excessive hiss generated by many headphone amps), and a low output impedance to avoid altering the frequency response of some headphones, the impedance of which can vary substantially at a given frequency.
Being a true linear class A design, the Arcam rHead delivers absolutely no crossover distortion, a problem with the typical class AB designs as the audio waveform passes between the transistors. Its discrete output stages are fed by individual +/- 11V power supplies and the gain is fixed to offer low residual noise while exploiting the available dynamic range of the Texas Instruments PGA2311A resistive ladder volume control to which it is direct-coupled.
Also featured in Arcam’s flagship A49 amplifier, the PGA2311A is a digitally controlled analogue chip featuring independent audio channels and a maximum dynamic range of 120dB. Use of such a volume control eliminates crosstalk and tracking error and gives near perfect channel balance and exceptional stereo imaging at all levels. The volume control is adjustable over a range of 80dB in 1dB steps.
The rHead features a comprehensive protection circuit to protect both it and your headphones, metal film resistors in the signal path and low-noise power supplies to eliminate cross-interference between sections. All this technology is fitted to an extensively optimised 2 layer fibreglass printed circuit board housed in a die cast aluminium casing, similar to that of the recently reviewed irDAC-II. Both unbalanced (max 4V) and balanced (max 8V) inputs are provided, with a switch to toggle between the two, while both 3.5 and 6.25MM output jacks cater for virtually any pair of headphones. A remote control would’ve been a nice addition, but has been omitted here in favour of achieving the best possible sound quality at the price and beyond
The rHead supports headphones of impedances between 16 and 600 ohms and outputs 2W, 1.1W and 0.13W into a 16, 32 and 300 ohm load respectively, all before clipping and at an output impedance of less than 0.5 ohms. Frequency response is rated at 10Hz – 20 kHz, total harmonic distortion + noise is a vanishingly low 0.001% and signal to noise ratio is rated at 109dB (A-weighted) both at 2V output into a 32 ohm load.
Power is supplied via an external 12V DC power supply, the rHead drawing a maximum 1.5A current. While it is technically possible to use a regulated linear power supply with the rHead (providing it can deliver at least 1A continuous current, its output doesn’t exceed +14V and doesn’t introduce an inverted ground loop), Arcam themselves state that such a power supply will likely offer no performance gain due to the extensive internal filtering, and that the unit will measure much the same regardless of the power supply used.
The rHead is packaged with some documentation, an RCA interconnect cable and a DC power supply. The power supply is supplied with a range of outlet adapters for various countries including the UK, EU, US and Australia.
Physically, the rHead closely resembles the recently reviewed irDAC-II, sharing its curvy (and weighty) cast aluminium casework, sitting upon a vibration-damped rubber base. Measuring 194 x 44 x 135mm (W x H x D), and tipping the scales at 0.71KG, it’s small enough to find a place in even the most cramped of equipment racks. It’ll need some airflow though, as being a class A amp it does produce some heat as evidenced by the temperature of the aluminium casing after just a few minutes of run-in time.
On the front, a rotary volume control doubles up as a mute switch, with an LED indicating the unit’s power and mute status, changing from orange to Green when you turn up the volume thereby disabling the mute function. You’ll find the 2 output jacks here too, both of which are extremely high quality terminals which firmly grip the jacks providing a solid mechanical and electrical connection.
On the back you’ll find the connectivity, including the unbalanced inputs in single-ended RCA form, and the balanced inputs via a pair of XLR terminals. These terminals are also of excellent quality, as is the switch used to toggle between them. Rounding off the connectivity, there’s a power switch and a DC power input jack. It’s worth noting that unless the power switch is switched off when not in use, the amplifier remains powered and thus will produce some heat when idle.
In use, immediately obvious is the rHead’s low residual noise. Using the rHead with a highly sensitive pair of 32 ohm headphones the noise is inaudible in an average room setting, and barely discernible as the faintest hiss in an isolated studio environment. Switching to something a little more difficult to drive, the Arcam impresses with an output level that belies its power output. The amplifier will seamlessly switch to class AB when necessary to drive low impedances at extremely high levels. In reality you’ll always hear the amp running in class A, as such levels are deafening and not something that a person with average hearing could sustain for any length of time.
The rHead offers up a sound that is crystal clear and, as you would expect, completely free from distortion. With treble extending seemingly into infinity, exceptional timing and exquisite bass control, the rHead paints a musical picture that is simply stunning and reveals levels of musical detail that you never thought possible. Arcam don’t build products that sound ‘hi-fi’ on a first listen but are ultimately fatiguing, and this condition continues with the rHead. You can listen to it for hours, and even after an extensive break-in period it gets better the longer you listen.
I tried a range of headphones, from Sennheiser’s budget HD202s to the HD650 and HD800, as well as models from Sony, Yamaha and Audio Technica. All headphones were driven without issue, reaching my preferred listening level long before the rHead’s volume had reached its maximum level. The rHead was able to equal the performance of a Sennheiser HDVA-600 at almost triple the price, even surpassing it when it came to musicality and listening enjoyment.
In summary, I simply don’t know how they do it. Another outstanding product from Arcam, and a real credit to the company’s existing product portfolio. At £399 in the UK and $599 in the US, it represents extraordinary value for money. Whether you’re a headphone aficionado or simply looking to add a headphone amplifier to your existing hi-fi system, the Arcam rHead should be at the top of your shortlist. Highly recommended.