I looked at Aiyima’s A07 MAX amplifier in the last post. They also sent over the A08 PRO, a more typical desktop amplifier though with Bluetooth and tone controls. Oh, and a VU meter.
The amp is supplied in a utilitarian box with simple documentation (not that you need it) and the power supply with a respective cable based on the shipping region. The UK plugs are correctly fused unlike some other Chinese amps, and the power supply has enough weight to inspire confidence.
Like the A07 the A08 is built around a chunky extrusion, though the A08 is quite a bit larger with a more sculpted design. The central dip is presumably designed to fit the Aiyima T8 tube preamp. I like it a lot, and appreciate the solid aluminium control knobs which feel nice to use.
Around back are an SMA screw-type connector for the included Bluetooth antenna, an RCA input pair, 3.5 mm buffered audio output, a power input and speaker terminals. The terminals will take 4 mm banana plugs and stripped wires. Spade connectors would be tight unless they’re particularly small. They aren’t the largest terminals, nor could they be given the space available, but they’re sturdy enough.
The A08 is still bereft of visible fixings on the front, though there is 1 on the top securing the front panel in place. The rest are on the bottom and around the back.
Not that there is much point in the average user disassembling this one, as there’s nothing that can be replaced inside. The audio components are surface mounted, and there’s no op-amp rolling fun to be had. Nevertheless, here are the internals.
We see three of those ubiquitous sealed potentiometers, two for bass and treble and one for volume with integral power switch. RGB LEDs are set either side of the volume to PROvide a status light ring around the control – red for line in and blue for Bluetooth. The VU meters are encased in an assembly bolted to the front panel. They’re responsive though only linked to the left channel so are more for visual appeal than anything else. I did notice a trend in the measurements that as power output rises, the discrepancy in performance between the channels suffers with respect to the right channel, which is generally about -3dB worse in terms of noise.
Beneath the heatsink is a Texas Instruments TPA3255 chipset, Aiyima claiming 300W per channel into a 4Ω load. You’ll need a healthy following wind, an allowance for 10% total harmonic distortion and a 48V 12A power supply to achieve anything close, though you can get about 90W into a 4Ω load and 55W into an 8Ω load at <0.1% THD. At a gain of 29dB and <0.007% THD you get a THD+N of -80dB, 5W Into 8Ω. Frequency response is quoted by Aiyima as being within 1dB. Measurements show the A08 PRO is flat through the audio band to within 0.6dB outputting 5W into 4Ω which is perfectly respectable for an amp like this.
If you would like to see full measurement data, you will find comprehensive tests at Archimago’s Musings, Audio Science Review, and this excellent video review.
My only concern is the power supply filtering. Aiyima specify the A08 PRO as being suitable for use with a 48V power supply. It is, but the primary reservoir capacitors are 50V rated components. Expect their life to reduce considerably if you choose to run the amp using a 48V supply. I would suggest Aiyima replace these with 63V rated components in PROduction, as there is plenty of space to do so. A bit of extra capacitance wouldn’t go amiss either, though the fast current delivery of a switch-mode power supply alleviates the impact to dynamic performance for the most part.
Inputs are switched automatically between the single RCA input and Bluetooth with a CD4052 two-channel multiplexer. It uses a Cirrus Logic CS4344 DAC, supporting 24-bit 192kHz resolution audio. Paired with a QCC5125 Bluetooth chipset the amplifier supports SBC\AAC\APTX\APTX-LL\APTX-HD\LDAC codecs for lossless streaming up to 48kHz over Bluetooth. Given that a lot of expensive hi-fi still doesn’t yet support AptX, let alone AptX HD, and touts it as an expensive selling point when they do, this is excellent.
The rest is a typical preamplifier implementation based around NE5532 op-amps with 6dB of boost or attenuation for treble and bass though no turnover frequencies are quoted. Noise levels are respectably low though with very little hiss audible in use. Expensive amps from highly reputed manufacturers idle with a lot more noise than the Aiyima does.
Usability is nothing you wouldn’t expect. The amp defaults to its line in mode. If a bluetooth device is paired, the amplifier will switch to Bluetooth mode and the status LED will illuminate blue.
And how does it sound? exactly as you’d expect. Clean, clear and crisp with no obvious deficiencies in its output and no character of its own to speak of. Run within its limits it performs about as well as you might expect of a linear amplifier. I did notice a lack of dynamic performance compared to the A07 MAX, which has a significantly larger power supply reservoir for but uses an identical power amplifier chipset. But the two are quite different in their design, so that could just as easily be attributed to the preamplifier.
Aiyima’s A08 PRO is a cracking little desktop amp with high-res bluetooth for about £120. It has plenty of power to drive sensible loudspeakers and appears to be well built. Some of its internal components are running close to their ratings, especially with a 48V power supply. These are economy amps and the components aren’t the finest money can buy, so keep that in mind. But for desktop use or the basis of a budget hi-fi you really can’t go far wrong.
If you’d like one for yourself and would like to support my work, purchase your A08 Pro through Amazon using This Link. Amazon pays a small commission on each sale at no cost to you, and it helps keep independent sites like Audio Appraisal running.
