AIYIMA A07 TPA3255 Review (Amplifier)------audiosciencereview

This is a review and detailed measurements of the AIYIMA A07 desktop amplifier based on TPA3255 class D amplifier chip. It was kindly purchased new by a member and drop shipped to me. The cost is US $72 on Amazon including prime shipping. And as of this shipping, it also included a 32 volt, 5 amp switching power supply. Member also purchased and sent me a 48 volt/3 amp power supply which I also tested.

The case is standard budget audio affair:
AIYIMA A07 TPA3255 Review.jpg


The volume control feels cheep but does the job. The back panel terminals were way too small for my binding posts:

AIYIMA A07 TPA3255 Review back panel RCA.jpg


The DC input socket was quite stiff especially with the 48 volt power supply. Tightness is not a bad thing as far as power transfer is concerned but this was a bit too stiff. Here are the two power supplies:

AIYIMA A07 TPA3255 Power Supply.jpg


They both feel kind of cheap as they would be at these prices ($21 for the 48 volt one). Personally I would not leave these plugged in permanently if I am not around. The included power supply has a two-pronged AC cable that was not polarized. Rotating it around made a small difference in mains leakage.

AIYIMA A07 Measurements
Let's start with our usual dashboard of 5 watts into 4 ohms:
AIYIMA A07 TPA3255 Measurements 32v 5 amp power supply.png


As you see in the FFT display, there is considerable amount of mains leakage at 60 Hz. This tends to be a function of switching power supplies. I played with grounding and improved it a lot in one channel but not in the other (not shown). SINAD did not get impacted since it is bound by distortion harmonics. As it is, performance is above average:
best desktop stereo amplifier review.png


Signal to noise ratio is not great due to the mains hum:
AIYIMA A07 TPA3255 Measurements 32v 5 amp power supply SNR.png


Frequency response is well behaved, albeit with a slight droop at 20 kHz:

AIYIMA A07 TPA3255 Measurements 32v 5 amp power supply Frequency Response.png


Crosstalk is good and well above bargain basement desktop amps:
AIYIMA A07 TPA3255 Measurements 32v 5 amp power supply Crosstalk.png


Power is everything in a small amp so let's see how we do with 4 ohm load:

AIYIMA A07 TPA3255 Measurements power into 4 ohm.png


As expected, with low impedance of 4 ohm we are current limited so the 5 amp stock power supply does better, turning in 77 watts. Yes, the 300 watt rating is a fantasy but maybe it can do better with momentary peaks. Alas, its aggressive protection circuit would shut it down and not let me test max and peak power.

Naturally the higher voltage power supply does better with 8 ohm load where we become voltage limited:
AIYIMA A07 TPA3255 Measurements power into 8 ohm.png


Sweeping power vs frequency and distortion shows a very well behaved class D amplifier:
AIYIMA A07 TPA3255 Measurements power into 4 ohm vs frequency and distortion.png


Conclusions
Traditionally these desktop amplifiers have produced really poor performance in the form of noise and distortion. Not so anymore. These TPA3255 based amps seem to have good bones in them, producing above average performance for peanuts. Alas, you are saddled with two boxes and cheap and potentially non-safety compliant parts. For desktop use, these are probably acceptable compromises.

I am going to recommend the AIYIMA A07 based on its performance.

And with this, our last review of 2020 comes to an end! Nice that it is ending on a happy note. :)

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