WiiM Amp Pro Streaming Stereo Amplifier Review

[early rejecter]

May I ask what streaming service is so critical, and is supported by Sonos, but not by Wiim?

Don’t know about the OP, but in my case it’s Apple Music that keeps me tied to Sonos. Sonos is (as far as I know) the only non-Apple streamer that supports Apple Music natively (i.e. via direct streaming, not Airplay from another device).

 

[amirm]

No FTC-like measurement?

If you look at the time stamps on these measurements you will notice they were done on the 19th. That is before the last couple of reviews. Company asked me to wait a bit to post the review which I did. I then developed the FTC test for the later reviews. I believe the amplification is the same in Ultra? If so, i will run it on that.

 

[Inertiaman]

I believe the amplification is the same in Ultra? If so, i will run it on that.

No amplification in the Ultra (well, other than the headphone amp that is). Ultra is a feature/performance extension to the Pro Plus streamer.

 

[Joffy1780]

It's a fine device. I don't think it was needed in the lineup.

How many more customers are they going to serve with this vs the regular amp? The design and production resources should have gone elsewhere, no?

Make a remote subwoofer device!

The only real additional resources have gone into the PFFB, which I think they had planned to implement in the original 'Amp'
but said at the time of launch they had not been able to implement it correctly. The design and production is the same as the original in every other area.

That said, yes, I want a wireless sub device as well, I discussed the idea with Wiim customer support perhaps as long ago as last year on the Wiim forum. They are (understandably) probably focussing on the Ultra launch and subsequent launch of their 'CI' range. I'm still hopeful, though.

 

[amirm]

No amplification in the Ultra (well, other than the headphone amp that is). Ultra is a feature/performance extension to the Pro Plus streamer.

Ah! I am so behind in all these products.

 

[Joffy1780]

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 and costs US $379.
View attachment 394860
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.
View attachment 394866
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:
View attachment 394868
That is excellent performance, landing the WiiM pro in that very class in our rankings:
View attachment 394870
I am showing the non-pro version in dashed highlight, indicating good level of progress made:

View attachment 394871

Analog input is digitized so doesn't have the same performance but should be good enough for a turntable and such:
View attachment 394872

Noise performance is excellent:
View attachment 394873

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:
View attachment 394874
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:
View attachment 394875

That results in less than stellar 19+20 kHz intermodulation distortion:
View attachment 394876
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:
View attachment 394877

Digital crossover works as expected:
View attachment 394878

Let's see how much power we have into 4 ohm load:
View attachment 394879
Output is limited to avoid clipping. 117 watts is plenty though for where this amp will get deployed. 8 ohm works the same way:
View attachment 394880
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:
View attachment 394881
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:
View attachment 394882
View attachment 394883

Amplifier is stable at power up:
View attachment 394884

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.

P.S. Yes, I have the Ultra version as well. Hope to test that soon.

------------
As always, questions, comments, recommendations, etc. are welcome.

Any donations are much appreciated using: https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/

Brilliant, thank you for the review.
Can't wait for the Ultra review.....which has to be the most eagerly anticipated ASR review for a long time!

 

[Inertiaman]

That said, yes, I want a wireless sub device as well, I discussed the idea with Wiim customer support perhaps as long ago as last year on the Wiim forum. They are (understandably) probably focussing on the Ultra launch and subsequent launch of their 'CI' range. I'm still hopeful, though.

For those wanting a wireless subwoofer device, why not simply use a Wiim Mini?

Sync it with your main listening component (Amp, Ultra, whatever). You can't manually adjust the delay timing, but the automatic delay adjustment of the Wiim sync function is pretty effective in my experience. You can use the Mini's 10-band PEQ to implement filters to augment or replace similar functions on the subwoofer.

 

[quattro98]

This is a no go in our home due to the lack of Airplay 2. I just ordered a WiiM amp to simplify a rarely used zone system.

I wish Apple would make Apple Music available as a direct service through products other than the Apple TV. Maybe I'll try Sonos for simplicity, but for extra rooms, Airplay 2 has been ok.

 

[Mort]

For those wanting a wireless subwoofer device, why not simply use a Wiim Mini?

Sync it with your main listening component (Amp, Ultra, whatever). You can't manually adjust the delay timing, but the automatic delay adjustment of the Wiim sync function is pretty effective in my experience. You can use the Mini's 10-band PEQ to implement filters to augment or replace similar functions on the subwoofer.

I don't think the mini does true sub DSP

 

[Inertiaman]

I don't think the mini does true sub DSP

What do you want it to do that a 10-band PEQ can't?

 

[Joffy1780]

For those wanting a wireless subwoofer device, why not simply use a Wiim Mini?

Sync it with your main listening component (Amp, Ultra, whatever). You can't manually adjust the delay timing, but the automatic delay adjustment of the Wiim sync function is pretty effective in my experience. You can use the Mini's 10-band PEQ to implement filters to augment or replace similar functions on the subwoofer.

So what I had discussed with Wiim was to repurpose a 'Mini' so that it can be permanently linked to another Wiim device, but benefit from the bass management with adjustments for crossover, delay and gain settings that you have on the sub out connections on the Ultra, Amp and Amp Pro.
You could certainly use a mini as you suggested, but once you group Wiim devices they are currently limited to 16/48 and you wouldn't have the same flexibility with the settings.

 

[Mort]

The only real additional resources have gone into the PFFB, which I think they had planned to implement in the original 'Amp'
but said at the time of launch they had not been able to implement it correctly. The design and production is the same as the original in every other area.

That said, yes, I want a wireless sub device as well, I discussed the idea with Wiim customer support perhaps as long ago as last year on the Wiim forum. They are (understandably) probably focussing on the Ultra launch and subsequent launch of their 'CI' range. I'm still hopeful, though.

There's always significant resources attached to having any new product. Not just the engineering. But sure the opportunity costs are not nearly as big as then adding a completely different device.

Still this feels so incremental and unlikely to really extend the reach of the amp line. Do we really care now now the Pro vs Pro Plus streamer? Another incremental upgrade

 

[ryanmh1]

Translate into percentages, the distortion of - 54 dB at 15 Khz, - 62 dB at 10 Khz and - 68 dB at 5 Khz... and you will undoubtedly be less disappointed.

.20%, .08%, and .04%. Audible or not, that translates right into "not good" by any reasonable metric. It also suggests it is prone to IMD, which in fact it does exhibit. Audible? I'll leave that for someone else to judge. But as an amplifier it's not impressive. This is objectively bad, and in a Class AB would indicate no feedback or a very poor implementation. This isn't Class D done well. It's mediocre technical performance (which is exhibited by many of these chip amps) in a lightweight, small package. Meh. I'll take a Fire HD 10 tablet on a charging stand with a USB DAC hooked to amp of choice over this, thank you very much.

 

[Petrushka]

May I ask what streaming service is so critical, and is supported by Sonos, but not by Wiim?

The multi-room sync capabilities of the Wiim products are astonishingly easy to use and perform flawlessly. And VERY cheap in comparison to Sonos. I guess if you're already heavily invested in the Sonos ecosystem then inertia alone keeps you there. But if I were starting from scratch today on a multi-room streaming audio setup, Wiim is a no-brainer.

Audible, XM

Accounts for 75 percent of my listening.

The main draw of Sonos is multi-room sync over WiFi. Even with the busted app, it just works.

Plays CD quality lossless without hassle.

The port has coax out. Bummer that the Wiim Amp only has optical in, but the adapter is $15.

I’ve sent two months thinking about this. In five or ten years my son will inherit all this, and he’s committed to Sonos.

I do have a use for two more Wiim amps.

 

[Inertiaman]

So what I had discussed with Wiim was to repurpose a 'Mini' so that it can be permanently linked to another Wiim device, but benefit from the bass management with adjustments for crossover, delay and gain settings that you have on the sub out connections on the Ultra, Amp and Amp Pro.
You could certainly use a mini as you suggested, but once you group Wiim devices they are currently limited to 16/48 and you wouldn't have the same flexibility with the settings.

Agreed, that would expand the performance and feature options. I made a similar suggestion to Wiim in one of their forums, essentially a SubMini. Sure seems it could be done with only firmware changes and no hardware changes.

 

[shuppatsu]

Audible or not, that translates right into "not good" by any reasonable metric.

My "metric" is that a "good" amp is one that is perfectly transparent to me at any volume I'd want to listen, given my mediocre ears and typical auditory processing. A "great" amp is one that is perfectly transparent to everyone. Is this not reasonable?

I don't know how you can evaluate an amp's performance without reference to audibility. Once something is transparent, better measurements don't make it more transparent.

 

[restorer-john]

No FTC-like measurement?

There's no such thing as an "FTC-like measurment". Unfortunately, it has little value in the context of Amir's reviews or the method he uses at the moment. You either do it properly or not at all. Where's the 1hr preconditioning? Where is the confirmation of THD+N for 250mW to rated power, 20Hz-20kHz? He pulls the plug at 15kHz and it's already -70dB/0.03% at 250mW and at just 80W/4R it's -54dB/>0.3% THD! You can see how little value the headline 1kHz@5W figure has.

He wound the power up at 1kHz and then swept from 20Hz-20kHz which is back to front. The rating specified is what is achievable (power) at the rated distortion (or 1%) from 20Hz-20kHz. You test to that advertised specification and confirm whether the device achieves it or not. You don't make up your own random method.

1kHz power is always greater than full bandwidth power. It's a lot harder for any amplifier to achieve full rated power at the frequency extremes and that's why full bandwidth rated power is the official FTC spec, not 1kHz. 1kHz ratings have always been the provence of manufacturers trying to over-rate their gear and deceive customers. It is a scourge of HiFi.

This wiim-amp-pro looks like a decent value, cute single box "solution" for people who want convenience and adequate performance- that's all. There's nothing here for a serious audiophile wanting to push the envelope of performance and I agree with @mcebrian and others comments in the same vein.

 

[Sokel]

There's no such thing as an "FTC-like measurment". Unfortunately, it has little value in the context of Amir's reviews or the method he uses at the moment. You either do it properly or not at all. He can stick to his 1kHz 5W number. Where's the 1hr preconditioning? Where is the confirmation of THD+N for 250mW to rated power, 20Hz-20kHz? He pulls the plug at 15kHz and it's already -70dB at 250mW and -54dB/>0.3% THD by then!

He wound the power up at 1kHz and then swept from 20Hz-20kHz which is back to front. The rating specified is what is achievable (power) at the rated distortion (or 1%) from 20Hz-20kHz. You test to that advertised specification and confirm whether the device achieves it or not. You don't make up your own random method.

1kHz power is always greater than full bandwidth power. It's a lot harder for any amplifier to achieve full rated power at the frequency extremes and that's why full bandwidth rated power is the official FTC spec, not 1kHz. 1kHz ratings have always been the provence of manufacturers trying to over-rate their gear and deceive customers. It is a scourge of HiFi.

This wiim-amp-pro looks like a decent value, cute single box "solution" for people who want convenience and adequate performance- that's all. There's nothing here for a serious audiophile wanting to push the envelope of performance and I agree with @mcebrian and others comments in the same vein.

I'm talking about this one which is better than nothing I suppose:

Even that way was revealing for JBL which gave up at 63Hz.
(now imagine if all conditions were met)

 

[amirm]

He wound the power up at 1kHz and then swept from 20Hz-20kHz which is back to front. The rating specified is what is achievable (power) at the rated distortion (or 1%) from 20Hz-20kHz. You test to that advertised specification and confirm whether the device achieves it or not. You don't make up your own random method.

It makes no sense to use every manufacture's spec. You won't be able compare one product to another then. My method expands on 1% THD (if possible) at 1 KHz to see if it holds across the full audio spectrum. By using the same method in every review, the results will be comparable to other products I test. Just because a government bureaucracy created something, it doesn't mean we should follow it like lemmings.

 

[elmoe420]

Audible, XM

Accounts for 75 percent of my listening.

These work fine via Alexacast. Have you tried that?

I assume they should also work fine via Chromecast. However, at less than 20$ for an Echo which is setup to use the WiiM as it's default speaker, that is a very convenient and cost effective solution in my opinion.