Aiyima A07MAX

Aiyima A07MAX - An outstanding Amplifier for the price

The A07MAX is Aiyima’s latest class D amplifier based on the TPA-3255 chipset. In this review, you will find out if it’s their best yet. I will provide some measurements, but also lots of details on the features and some comparions so hopefully by the end of the review you will have a clear idea of what the A07MAX provides.

So before we get into the features and comparisons of the A07MAX - let look at some measurements:

Measurements

Note: I will update this review with independent measurements when they become available but for now here are Aiyima’s own measurements from their AP Analyser:

First the THD+N / SINAD score:

Its hard to see in the above screenshot but the THD+N is 0.00742% which translates to a SINAD score of 82.5 so very similar to the A07 (and other TPA-3255 based class D amplifiers so its an excellent score).

Note: Ultimately moving to using a more expensive PFFB circuit is probably the only way the TPA-3255 to perform significantly better.

Next the SNR score:

So again hard to read but this shows a SNR of 107 dB - which is excellent (roughly 17 bits of dynamic range so excellent quality).

Finally, checking for load dependencies:

Again this is an excellent meaurement, showing an even response with a very a slight roll off after 10K.

Features

The features of this amplifier might look minimal at first glance but for amplifiers it is often a case of less is more. Effectively, the A07MAX starts with a similar minimal feature set as the A07 (and in fairness similar to the Fosi Audio V3) but then it provides the perfect upgrade path with its ability to be switched into a Monoblock configuration.

But to understand the A07MAX features it important to have a understanding of where it came from:

A brief history of TPA3255 amplifiers

The Aiyima A07 was the first “cheap” class D amplifier recognised by the audio community as “audiophile” quality yet at a nice price for those starting off in the hobby of home audio.

It provided clean / neutral sound without the noise / “tinny” sound of previous class D amplifiers in the equivalent price range. It was praised by subjective “YouTube” audio reviewers like the CheapAudioMan yet also highly praised by objective reviewers from AudioScienceReview and others for its excellent SINAD / THD+N values (meaning it provided clean audio without distortion at high levels of output with a neutral accross bass, midrange and treble). There were other competitors in this market but Aiyima iterated over the design of the A07 with the A08 and a number of other class D amplifiers adding more features like bluetooth / tone controls etc to the basic TPA3255 design.

But recently one of their competitors (Fosi Audio) went “back to basics” with their design for the Fosi Audio V3 - not adding “features” but using higher quality components, a new orientation of the amplifier board and better cooling to provide a high quality alternative to Aiyima TPA3255 products.

So I love competition in the audio industry and I was very interested to see what Aiyima would do in response to this challenge and I am glad to see that the Aiyima A07MAX is a great response to the Fosi Audio V3.

Sound quality

As I mentioned earlier the most important feature of the A07 is how clean and neutral sounding it is at all volumes. It can go impressive loud yet never looses composure (especially with the supplied 36V power supply).

The volume control is very smooth and subtle (though it uses a more linear volume than the logarithmic volume control on the Fosi Audio V3).

I found with a Monoblock configuration it was even cleaner sounding especially when fed separately from a pre-amp. For the price I do not believe you can get a better sounding amplifier.

Key Features and Comparisons

What the box looks like:

1. New Design and the Board layout
   I think the wider design on the MAX allows allot more space at the back of the Ampflifier - meaning cables are well separated - see photo below. They effectively redesigned the MAX so it’s wide instead of deep. See picture below of the base of the MAX:
   

2. Nicer binding Posts
   The “offset” of the binding posts is much better and I think they have much higher quality binding posts than the V3,

3. Mono block mode (and the switch)
   This is an exceltional option IMO - it shows off the upgradability - i.e. start with 1 A07MAX in stereo, then buy a second one and setup each as a Mono Block Amplifier (with a pre-amp controlling the volume)
   
   See below for mroe details on the Monoblock setup.

4. Vent holes on the side to keep the amp cool:
   

Running as a Monoblock

Aiyima provide a simple diagram (they provide a different one in the manual but I think this is their updated one from their website):

As you can see you run the left and right audio from a pre-amp into 2 A07MAX then run the ‘mono’ marked + / - binding posts into your 2 speakers.

Here are my 2 A07MAX setup a Monoblocks being fed by a MiniDSP as a preamp:

The reverse connections - note this was using the alternative connection using one of the Aux outputs:

Motherboard layout

The internal layout of the A07MAX looks good and I believe their new design has been optimised for minimising the heat when used for extended periods:

Power supply options:

Mine came with a fairly basic 36V power supply:

As for powering A07MAX has excellent choices with power supply especially when using it in PBTL Mono mode (in a dual mono-block configuration):

What could be improved

Very little at the price. But here are 5 things Aiyima could do in a future A07MAX ( maybe A07MAX Pro ):

1. Separate On/Off switch
   This would allow the volume to be fixed yet switch it on / off, useful when using a preamp and having the A07MAX in Monoblock or with an external Subwoofer.
2. Balanced Inputs
   Adding a ‘Pro’ to the name would probably bring it certain expectations, such as the ability to feed either balanced or RCA inputs (e.g. like a Topping PA7 )
3. Volume Bypass switch
   Again this would be useful when in Monoblock setup with an external Pre-amp controlling the volume. With a switch there is no accidental moving the volume on the A07MAX
4. 12V (input and output)
   It would be nice to be able to ‘remotely’ control the A07MAX via a trigger, e.g. A Wiim Pro Plus might be act as a pre-amp to 2 A07MAX’s and its 12V trigger would wake up one A07MAX and that one could be chained to wake up the 2nd A07MAX.
5. PFFB circuit By adding a Post Filter Feedback Circuit - the measurements would be considable improved but most importantly the amplifier would not be load dependent.

Rating

I gave this a pragmatic rating of 5 - it is almost perfect for the price - can’t wait to see what happens next with the competitive nature of this market.

Summary - A new standard in Class D amplifiers

I have had a few class D amplifiers over the past few years - some from Aiyima like the A07 and A08Pro were excellent and some from competitors like the Fosi Audio V3 but this new A07MAX is quiet simply a new standard for what we should expect from a class D amplifier.