This is a review and detailed measurements of the Topping PA5 stereo desktop amplifier. It was sent to me by the company and costs US $349.
PA5 enclosure looks like their standard DACs and such:
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Hard to imagine that an amplifier can fit in the same size but here we are. There are large slots for cooling on the bottom and sides which worked well to keep the unit cool during testing.
Back panel shows dual inputs which is nice:
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The beefy power supply reminds me what used to come with large gaming laptops. It is rated at 38 volts and 4 amps. In use, its temperature did not even rise above room temperature so I imagine it has good bit of headroom. Connection is a secure, screw on, two pin din style which I much prefer to flimsy barrel connectors used in many desktop amps.
Back to inputs, they are TRS balanced input which is fine by me. If you don't have such balanced cables, you can either use an adapter or get an XLR to TRS cable which is what I use. The compact form factor of these allowed it to have two such inputs instead of just one.
Speaker binding posts are the usual small ones on desktops but here they are spread apart thankfully which gets rid of 90% of the aggravation of inserting my large, locking banana plugs into them.
Note that there is no remote and volume control is the traditional one (not rotary). So if you need a remote, you should use a DAC with such and leave the amp with fixed volume.
Topping PA5 Measurements
As usual, we start with our dashboard:
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Wow, it has been a long time since I have seen such great SINAD score. Rounding it, it lands at 106 which puts it second in a list of over 160 amplifiers tested to date!
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Typical desktop budget amp struggles to get in the green. The better ones are in the upper half of the green. The PA5 is not only in blue but almost at the top of it. This is incredible achievement.
Yes, there is a bit of "cheating" going on in the form of low gain of 19 dB. Benchmark AHB2 which landed on top used the same. In practice, this is not a problem at all since max power was achieved at 2.5 volt which is well within the 4 volt range of balanced DACs.
And this is one extremely quiet amplifier:
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My standard at 5 watts is 96 dB or 16 bits of dynamic range. PA5 sails past that to 18 bits or 107 dB. Just remarkable. Many amps can't even get to 96 dB. At full power, it clears 20 bits of dynamic range which means even then the noise it produces is below threshold of hearing.
Multitone test shows some distortion rise with frequency but still remarkably low:
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I am always nervous running the frequency response test on class D amplifiers, worrying that their output filter interacts with the load and cause audibility issues. That was a worry for not:
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Yes, there is some variation but the design has made sure that happens a) in ultrasonics and b) with very low amplitude of change. We can see the reason for this in wideband FFT spectrum analysis:
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Class D amps usually run at a frequency of 300 to 400 kHz. PA5 pushes this up to 600 kHz. This gives the output filter more room to roll off the response where its ringing is above audible band. Unrelated, we also see a super clean spectrum here. None of the usual messiness is here which we even see in high-end class D amps. Attenuation of the switching frequency is almost 40 db and not the usual 10 to 20 dB.
Crosstalk is extremely low:
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Considering how tiny this package is, I am so pleasantly surprised to see this level of performance.
Despite the tiny package, we have good bit of power into 4 ohm:
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Allowing for 1% distortion, the available power naturally goes up even more:
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Naturally switching to 8 ohm, cuts the power:
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But notice how the PA5 matches and slightly outperforms the noise level of our current class D champ, the Purifi.
Sweeping the frequency vs power and distortion we get:
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We usually do not get curves that point down this much. This happens when distortion is so low that noise dominates. So very good showing there. Yes, there is rise in higher frequencies but we are starting at such a low baseline that this is exaggerated compared to other amplifiers.
Topping PA5 Speaker Listening Tests
I am confident of the transparency of this amplifier with respect to noise and distortion. However, I was curious how far its power goes. So I hooked up the PA5 to my Infinity Reference 253 speaker. I must stay, I was not prepared for the level of impact, fidelity and overall quality of the sound. The PA5 grabbed the ears of this speaker and pulled it any direction music asked it to like nobody's business! There was thundering bass. Superb high frequency and ability to fill my space despite only playing one speaker. It was hard to imagine this little amplifier powering this speaker so beautifully.
Conclusions
It is abundantly clear that ton of great engineering has gone into the design of Topping PA5. It breaks all barriers as far as noise and distortion, not only in its own budget/desktop class, but way, way outside of that. If it had double the power, it would obsolete all of them and in a hurry! As it is, I would certainly use it in a desktop or secondary system. And even primary if you are not going to blast the volume with super inefficient speakers.
It is my absolute pleasure to recommend the Topping PA5. The dynamics of stereo amplifier market just changed folks!
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