wiim amp pro ASR review
This is a review and detailed measurements of the WiiM Amp Pro networked streaming stereo class D amplifier. It was sent to me by the company.
The package is minimalistic in nature and matches the “non-pro” version of the amplifier. The volume indicator is that set of LEDs. They are modulated though to show partial levels with dimming which is nice. The included app is quite sophisticated with many features which is one of the key differentiators for the company products. This revision adds PFFB (post filter feedback) which should do away with the load dependency of the non-Pro version.
Back panel shows nice inclusion of HDMI ARC (I still can’t test this) and sub/mains output which actually works since you can apply filters to both.
Digital inputs are in the form of streaming and Toslink. Nice to see inclusion of power supply which is rare in this price/power class.
If you are not familiar with the measurements that are about to follow, please watch my tutorial on testing power amplifiers:
WiiM Amp Pro Measurements
Let’s start with toslink input and our usual 5 watt output of 1 kHz tone:
That is excellent performance, landing the WiiM pro in that very class in our rankings:
I am showing the non-pro version in dashed highlight, indicating good level of progress made:
Analog input is digitized so doesn’t have the same performance but should be good enough for a turntable and such:
Noise performance is excellent:
Even at 5 watts you easily clear the hurdle for 16 bit audio which many at much higher cost amplifiers fail at.
Let’s get to the main test, which is frequency response:
We see peaking but it is outside of the audible band and at any rate, shows essentially no difference with the two load impedances. PFFB works!
Multitone performance is very good up to lower treble but then it rises some:
That results in less than stellar 19+20 kHz intermodulation distortion:
Fortunately there is zero content out there with full amplitude 19 and 20 kHz tones so practical impact is nill.
Crosstalk/channel separation is excellent:
Digital crossover works as expected:
Let’s see how much power we have into 4 ohm load:
Output is limited to avoid clipping. 117 watts is plenty though for where this amp will get deployed. 8 ohm works the same way:
Keep in mind that most speakers have 4 ohm impedance in low frequencies where there is most demand for power.
Changing frequencies highlights the rising distortion with frequency yet again:
Ability to produce the same power at 20 Hz is impressive for such a compact design.
Reactive loads are handled well as long as you stay at 4 ohm and higher:
Amplifier is stable at power up:
Sorry, forgot to capture thermal image. The package insulates the insides anyway so wouldn’t be very accurate.
Conclusions
Just about every measurement has subjective assessment of “excellent” showing the company has paid attention to all aspects of the design. It is in every way improved over the original version which warms my heart. 
Functionality is top notch with streaming and sophisticated app support. Price is quite reasonable for all this functionality, power and performance.
I am happy to recommend the WiiM Amp Pro.
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