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WiiM Pro - Review & Measurements (Streamer)

VintageFlanker

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WiiM Pro - Review & Measurements

Main.jpg

Hey folks,

It is time for my first review of 2023... This one is about a complete objective analysis of the new WiiM Pro streamer. The aforementioned has been recently announced, back in November 2022, and I can see quite a strong hype around it since. That is really not surprising : the WiiM Pro comes with a lot of promises : It is claimed to be a "bitperfect" streamer transport, as was the WiiM Mini, now with the addition of cool features, like some S/PDIF pass-trough, Google Chromecast built-in, or (yet to be added) Multiroom and Roon Ready support.

At only 179€, it may sound like real bargain, especially when considering this could be the cheapest Roon Ready product ever. It is important to point out that the latter function is still not available by the time of this writing, even after the last (02/15/2023) update. The WiiM team publishes and constantly updates their roadmap on their website (which is rather uncommon from most manufacturers, and as such, welcomed), and the WiiM Pro appears to be currently under certification with Roon. Please note that Roon users may already use the WiiM Pro, when selecting it as a Roon Endpoint (through Chromecast).

These asides, it mostly has the same features, and presumably the same DAC and ADC chips, as the WiiM Mini, but with extended connectivity. By bringing such a complete unit to the market, there is no doubt that WiiM is aiming to compete against well-installed and popular products like the Bluesound Node, but at almost 1/4 of the price. Speaking of price, I bought myself this sample, tested today, on Amazon. By the way, availability is yet to be optimized, especially in EU.​

Front.jpg


The WiiM Pro comes in a little and quite light plastic box. While I did not expect much in terms of overall build and finish, considering the features/price ratio, I am still kind of disappointed. The plastic feels a bit cheap on touch and I don't like the grey tone and texture. However, I appreciate the non-slip covering beneath it, that allows the unit to remain stable when plugging cables or using the touch buttons. As you can see, these are four, for either volume control up and down, play/pause and preset. I found them to be decently responsive, but pressing them doesn't display anything, unless the main LED that is blinking. Not sure if these will be used much, since the unit has to be entirely controlled by the App anyway.​

Back.jpg


On the back, I am please to see a rich connectivity for such a small unit. We got both RCA inputs and outputs, two optical sockets (in and out), one coaxial output, a 12V trigger out, wired LAN input, and a mic, probably to be used for Alexa or any assistant (I do not use these). The power is done by the USB-C input (USB cable and 5V/2A adapter supplied). I also like to not have any antenna, when knowing the WiiM Pro also supports both Wi-Fi and Bluetooth. By the way, I encountered no range issues, cuts, nor skipping, when using these two wireless inputs. It supports up to 24bits / 192kHz with Wi-Fi, Optical and Coaxial or 96kHz for Chromecast. Bluetooth (5.1) is unfortunately limited to AAC and SBC codecs.​

This is how the WiiM Home App looks like :

Screenshot WiiM App + Roon.jpg


While this review is largely measurements-based, I used the WiiM Pro in my system during about a week, which is enough to share my two cents. I liked using it. It worked. That is it.

More seriously, yes, I have to admit I was a bit scared about getting something... more flawed. When you launch such a packed product at this price, then compromises are done, and software is usually the first victim... Well, not here ! The app is overall pleasantly stable and smooth. I like to see some cool additions like the bitrate to be displayed (like does UAPP). What I did not was the absence of "melting" artists and albums between different streaming services (as does Roon) when using the search button. I would also wish for a clearer way of displaying outputs and inputs settings. Apart from that nitpicking, WiiM Home does not compare unfavourably to other ecosystem on the market like BluOs, HEOS, MusicCast, StreamMagic and so on. In fact, I even preferred it over some of the aforementioned.

WiiM Home asides, the WiiM Pro (through Chromecast) worked flawlessly when controlled by either Tidal Connect, Qobuz Connect, and Roon.

These being said, it is now time for...

Measurements

Disclaimer: Measurements you are about to see are not intended to be as precise or extensive than what you get from a 30k€ AP. There is obviously both hardware and software limitations here, so not quite apples to apples comparison with Amir's testing. Still, this data is enough to have a pretty good idea if the gear is bad or not, stellar, broken, or sub-par...

- Instruments : E1DA Cosmos ADC (Grade B). Minimum phase filter. A newcomer is the RME ADI-2/4 PRO SE, which, 1) does a better job measuring unbalanced and low level signals, 2) may record and measure digital signals. E1DA Cosmos APU 60dB preamp is used for DR measurements. Output voltage is measured separately, using a DMM with a 0dBFS 1kHz tone.
- Software : REW V5.20.14, Multitone Loopback Analyzer 1.0.74 and RMAA 6.4.5 PRO,
- Method : 8 runs for each test, then I choose the closest to the average. Bandwidth and sampling rate to be specified for each test.
- WiiM Pro is running 4.8.507636 firmware. Output, input and setting to be specified below.​


DAC Performance
Analog.jpg

Let's start with the DAC performance. For this first battery of tests, I measured the WiiM pro through its RCA output, set at fixed level, 2Vrms. Digital input is S/PDIF optical.

WiiM Pro - DAC Summary
Tests
Results
Rating
Frequency Response 40Hz; 15kHz​
-0.02; +0.05dB​
Very Good
Noise Level (REW)​
-110.9dBA​
Very Good
Dynamic Range (REW)​
104.3dB​
Good
THD (REW)​
0.003427%​
Good
THD+Noise / SINAD (REW)​
-88.8dB​
Subpar
IMD SMPTE (REW)​
-77.5dB​
Subpar
Stereo crosstalk (RMAA)​
-109.8dB​
Very Good
IMD+Noise at 10 kHz (RMAA)​
0.0118%​
Average
Multitone 64 TD+N (Multitone)​
-82.9dB​
Average

Note: In addition to the supplied USB adapter, I also tested the WiiM Pro with two different USB chargers, from either Google Pixel or Xiaomi, then with a 5V/2.4A battery/power bank. So far, I measured absolutely no difference to speak about (at least not in the 20Hz-20kHz range). That being said, every measurement to come have all been done with the battery.​

Total Harmonic Distortion + Noise (SINAD) - 24b/44.1kHz
Test 4.jpg

Note: SINAD performance is 100% the same when using the Wi-Fi input.​

Frequency Response - 24b/44.1kHz
REW FR DAC.jpg


Noise Level - 24b/44.1kHz
REW Noise level RCA.jpg


Dynamic Range - 24b/44.1kHz
REW DR 2 RCA 2V.jpg


Intermodulation Distortion SMPTE - 24b/44.1kHz
IMD SMPTE REX 2V RCA (R 77.9).jpg


Intermodulation Distortion SMPTE Versus Level - 24b/44.1kHz
IMD SMPTE VS Level.png


Jitter - 24b/48kHz
Jitter.png


Multitone 64 - 24b/192kHz
Multitone 64 - TD+N- -82.9dB.png


Intermodulation Distortion + Noise (sweep) - 24b/44.1kHz
imdswept.png


Crosstalk - 24b/44.1kHz
cross.png

What to say? The whole performance seems to be very similar to WiiM Mini, apart from Dynamic Range. Meaning: not quite OK. Overall, while far from being catastrophic, we are expecting much better by 2023 standards. Yes, some may point to the price, but no, we have seen cheaper unit performing better than this. Yes, not as features-packed, but at least suitable/transparent enough for 16 bits, what is not even the case here. At least, I cannot point one particular result showing a "broken" product (except IMD VS Level that is particularly poor, though) I would say that it is "cohesively subpar" performance... But, at least, the results are still a bit above manufacturer's specs: -86dB THD+N, 102dB SNR.​


Line Out Level
The WiiM Pro also comes with four selectable (fixed) output levels. While I did not test precisely the behaviour of digital attenuation at different level in the analog domain, (but I did catch THD+N at different digital volume below), I measured each of the output settings and expected a logical drop in performance. Yet, for some reason, the opposite happened:​
2Vrms : -88.8dB THD+N
1Vrms : -92.8dB THD+N
800mV : -93.1dB THD+N
500mV : -93.2dB THD+N

Finally, the best performance I could have measure out of the DAC has been when set at 0.5Vrms:​

Total Harmonic Distortion + Noise (SINAD) - 24b/44.1kHz
Rew FFT 0.5V RCA.jpg



ADC Performance
For these next bunch of tests, I compared the exact same analog signal, which is the RCA output of my Matrix Mini-i Pro 3, first measured by the ADC of the ADI-2/4 PRO SE, then measured by the ADC of the WiiM Pro (and finally, the latter digitally recorded by the ADI-2/4 through S/PDIF). The obvious purpose is to observe how the WiiM Pro performs against a much higher end ADC. While being not Sate Of The Art, I considered the Matrix to be clean enough (about 109dB SINAD, SE) to not bottleneck the ADC performance of the WiiM Pro. And trust me, it did not !

Note: The WiiM pro cannot handle input signals when slightly above 1Vrms, which is according to manufacturer's specs. After quite a few tests, I lowered the Matrix's output down to 1.05Vrms to get the best case scenario in terms of performance.

WiiM Pro - ADC Summary
Tests
Reference 1.05Vrms output
ADC
Frequency Response 40Hz; 15kHz​
+0.01, -0.02​
+0.01, -0.05​
Noise level​
-115.1dBA​
-97.1dBA​
Dynamic range​
113.5dB​
92.4dB​
THD + Noise / SINAD​
-109.8dB​
-88.8dB​
IMD SMPTE​
-103.5dB​
-80.2dB​
Stereo crosstalk​
-115.3​
-84.7​


Note: It appears that the WiiM Pro's ADC is using internal sampling to 48kHz, according to frequency rate displayed on the ADI-2/4. As such, measurements you are about to see are all done at 24bits / 48kHz.
Total Harmonic Distortion + Noise (SINAD) - 24b/48kHz
REW FFT ADC VS MATRIX (2).jpg

Ouch. That really is not great, and seems to be on par with @amirm measurements of the WiiM Mini ADC. This is the best performance that I could measure. When feeding the ADC with a slightly stronger signal (1.09Vrms), the performance degrades only by a few dB. However, we start to see the ADC clipping when reaching about 1.20Vrms. Above, we enter this scenario:

Total Harmonic Distortion + Noise (SINAD) - 24b/48kHz
REW FFT ADC Clippling THD 32.7.jpg

Needless to say, it is completely unusable. Which is a shame, when we know that the vast majority of analog sources out there are often rated 2V output voltage, not to mention without variable output... So if you planned to pair the WiiM Pro with, say, a regular CD Player, you will have to use the S/PDIF input or just forget about it...

Frequency Response - 24b/48kHz
tEST FR.jpg

There is some 0.4dB loss in amplitude over the original measured signal. It is still fair and most likely flat from 20H to 20kHz.

Noise Level - 24b/48kHz
REW ADC Noise Level.jpg


Dynamic Range - 24b/48kHz
REW ADC DR.jpg

Note: This is measured without the Cosmos APU, due to wiring limitations. Still enough to observe Dynamic Range differences between both ADC.​

Intermodulation Distortion SMPTE - 24b/48kHz
REW ADC IMD.jpg


Multitone 64 - 24b/48kHz
Multitone 64 ADC.png


Jitter - 24b/48kHz
Jitter ADC.png

Wow. This last one is a complete failure. I had to double-check this J-test several times to understand how it could be so wrong, but no, this is what you get after WiiM A/D conversion. Some may think the S/PDIF output of the WiiM Pro to be responsible, but it is not, as you will see later.

Overall, this is indeed a bad performance. I would personally not pair any analog source to this product, unless some (already poor) signal out of a phono preamp.

By the way, in case some may think about using it as an analog hub, this is the performance when using Line In straight to Line Out:

Total Harmonic Distortion + Noise (SINAD) - 24b/44.1kHz
REW FFT Analog In Out (L 81.7).jpg




Digital Performance
Digital.jpg

Alright, now we are entering a much more interesting (and cleaner) area. Because I assume that many WiiM Pro owners are intending to use it mostly as a digital hub, paired with a much better DAC than what we have seen above. (in fact, you all have to!). These next tests have all been done without A/D conversion and are 100% in the digital domain. I used either REW tone generator for S/PDIF inputs, or WAV test files tones from the Audio Precision's tone generator, then played through the WiiM Home App, or Roon. Results are directly recorded through S/PDIF with the ADI-2/4 Loopback.

Note: To state the obvious, zero difference has been observed between wired LAN and Wi-Fi connection (literary no reason there would). All tests have been done with Wi-Fi.

Let's start with the regular main (Wi-Fi) input:

Total Harmonic Distortion + Noise (SINAD) - 24b/44.1/192kHz
REW FFT WiiM App.jpg

As we might expect from any decent unit, we got a textbook, absolutely perfect 1Khz signal, with distortion and noise out of this world. Nothing to worry about if you plan to use the WiiM Pro that way. The rest will be up to your own DAC.

By the way, just for peace of mind, this is how the SMPTE IMD looks like :​

Intermodulation Distortion SMPTE - 24b/44.1kHz
REW SMPTE WIFI.jpg



Chromecast
Since the WiiM Pro does have a Google Chromecast bluit-in, that uses different protocols than the WiiM App, we have to check its specific behaviour. To do so, I used a 44.1kHz 0dBFS sine wav, played through Roon (and WiiM Pro Chromecast as a Roon Endpoint). We got this:

Total Harmonic Distortion + Noise (SINAD) - 24b/44.1/96kHz
REW FFT Chromecast Roon Updated.jpg

Note: This test has been done again after the latest update. Before that, Chromecast's performance was much worse (see there).​


S/PDIF pass-trough
I also checked both optical and coaxial outputs, hardly trying to find any difference...​

Total Harmonic Distortion + Noise (SINAD) - 24b/48kHz
SPDIF IN OUT.jpg

Note: I have read and heard some early adopters complaining about the S/PDIF showing some delay, for instance when used with a TV optical output. I noticed nothing of the sort (LG OLED C2), so my guess is that it has been fixed since.

Speaking about it, here are the jitter plots for both:​

Jitter Optical - 24b/48khz
Jitter Toslink Out.png


Jitter Coaxial - 24b/48kHz
Jitter Coax Out.png



EQ
When EQ is set On, it widely affects performance:

Total Harmonic Distortion + Noise (SINAD) - 24b/44.1kHz
REW FFT EQ FLAT.jpg

Obviously, you do not want to use EQ at fixed volume, unless 57dB SINAD (before D/A conversion) is something you are looking for... It becomes way cleaner with volume is unlocked, the lowered at about 95%. This issue could be easily fixed by firmware, by setting max volume about 1dBFS down.​


Bluetooth
For the last graph of all, let me introduce this horror show:​

Total Harmonic Distortion + Noise (SINAD) - 16b/44.1kHz
REW FFT Bluetooth.jpg

What a shame that the WiiM Pro does not support aptX HD or LDAC... These results are to be expetced and share the same profile than seen in @amirm measurments there (with even a touch worse implementation).

Digital Volume
Last but not least, a quick world about digital volume implementation. This is what I get when measuring the same 1kHz tone (Wi-Fi In, 44.1kHz) at different levels:

Fixed: -141.8dB THD+N
≃75%: -138.2dB THD+N
≃50%: -131.5dB THD+N
≃25%: -115.5dB THD+N
≃10%: -99.6dB THD+N

...Well, that is enough data for today! As I do not use these at all, I missed either DLNA and Airplay, but you have to expect 16bits/48kHz limitation for the latter. In my humble opinion, that would make no sense to use it over Chromecast. Edit: Added AirPlay (limited to 44.1kHz through Roon):
Total Harmonic Distortion + Noise (SINAD) - 16b/44.1kHz
REW AirPlay.jpg




Conclusions
I will try to isolate both my subjective thoughts and objective findings each others for a little... If looking only at overall pure performance, the WiiM Pro is kind of a mess. While not being the worst I have seen, the DAC portion is nothing near suitable for 24 bits content, far from what we should expect from a product launched in late 2022 (at whatever price), and actually surpassed by some dongles. The ADC is even weaker, not to mention almost useless if you do not have a variable output, thanks to its 1Vrms rated max input. Among other scenarios, it will probably not degrade (even more) some phono signal, but what would be the point to use a turntable for ending in the digital domain that way? You vinyl guys tell me...

On the other hand, we got the digital side. First, the app is cool, it works great, without noticeable bugs or lags. I enjoyed using it on a daily basis. Then, we have the unquestionable performance. It is indeed perfectly transparent when using Wi-Fi, and remains always stable even when streaming 192kHz tracks. The S/PDIF inputs/outputs are a great addition if you want, like me, a streamer feeding your DAC (with only one optical input), that may also catch a signal from a TV or another source. If I forget the (expected to be) poorly Bluetooth measurements, all digital inputs just work and measure great. Chromecast is one of the best addition over the regular WiiM Mini, since you may choose to bypass the WiiM Home App, using either Roon, or any major streaming service's dedicated app. I am personally still waiting for Roon Ready update, and would be glad to re-measure if the digital performance remains the same that way.

Weighting the pros and cons, I will give the WiiM Pro my recommendation, based on how I would (and will!) use it for myself. For the price, it just does its job, and in a great manner. Period.

Flanker rating:
WiiM Pro (analog in & out): Mediocre
WiiM Pro (digital transport):
Excellent
 
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Thanks a lot for the review!

They could have stripped the analog in and analog out and release it as digital only: would have saved some $, and spend the money in LDAC Bluetooth instead. Still a great digital streamer though.
 
Thanks for the detailed write-up which covers so many usecases. Very helpful. I'm going to use the coax out without eq so this unit will be a good replacement for my Yamaha WXC-50. Really looking forward to experiencing the wiim app.:D
 
Very well done !
And your graphs are easily readable, which is not that common and so important for the reader.

I'm still puzzled by the high level of the second harmonic out of the DAC.

Even in DR measurement, with an output signal at -60dBFS (or around 2mV), it shows.
I think that's the first time I see that.

Do they increase it on purpose ?
 
Your shots of the UI were the most interesting part to me - I've never gone to the "Browse" screen because I use mine strictly as an AirPlay receiver and digital source switcher (Parks Audio Puffin phono pre plugged into it, via coax-to-toslink converter box, to get benefit of the 12V trigger). I didn't know they had a source switcher in that menu.

That's really my only complaint (once they fix the auto-off behavior with optical input) - they should make it easier to switch sources. Ideally one should be able to do it from the "device" screen. Also on the "Browse" screen you should be able to put source selection on top. On the plus side, in our house at least the current kludginess of changing inputs means I'm the only one who will ever touch the turntable...
 
congratulations for this "enormous" job...

there is just one big precaution to take..
it is to realize that most of the observations in the digital domain on the digital outputs are dependent on the spdif input processing etc of your measuring device... here it is a strong processing which will level the results..
it's funny because to do well.. you have to find acquisition solutions... not """good""", otherwise we will observe or especially compare not much..
rme num input is too good for that...it is him that we "measure"...
;-)))
 
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Thanks for the objective review, bears out the expected in the digital domain
Ordered one to replace a wiim mini
looking forward to using the 12 v trigger, with my NAD C 298 and minidsp SHD
planning to use the toslink out, just as I am with my wiim mini

For TIDAL usage, chrome cast Vs the Wiim app, any recommendations?
 
Many thanks for your clear and helpful review.
Shame about the DAC and ADC, but it looks like a fantastic digital streamer and great value.

Looking forward to PEQ implementation and measurements which might clarify reasons for choosing the Pro over the Mini (or not).

Kudos to WiiM - great product, even better attitude and support.
 
Got it for Tidal Connect (no MQA) to stream to Topping E50, no other expectations, but app is excellent and the device is very responsive. Any thoughts about the processor ?
Re. DAC, subjectively it sounds 'good enough' to me, I mean there are many ways to sound wrong and this one sounds 'bad' but acceptable (I mean comparing for ex. with HK Omni Adapt analog out). And the plastic case looks solid for the money.
 
Thanks, I will buy this (when I find one here in EU) to replace a Sonos connect from 2008 (I think it was), I am tired of the Sonos app, the S1 is unstable.
I will just use it as transport, the newere Sonos port cost a lot and is not worth the money im my opinion.

I was also interested in the new Nad CS1, but the wiim using Coax out will be perfect for me.
 
@VintageFlanker "Among other scenarios, it will probably not degrade (even more) some phono signal, but what would be the point to use a turntable for ending in the digital domain that way? You vinyl guys tell me..."

If u have entry level turntable like me (Project Essential II with Ortofon 20/ Thorens mm002 pre amp) and u know limitation of audio, used just of nostalgia and love of LP, and for not invest lot of money in PREAMP for NCore power amp... :)
 
Nice review Vintage Flanker!
Regarding the EQ capabilities of the Wiim Pro, is it fully customizable (frequency, q, gain etc…) or restricted to pre-defined frequencies?
 
Even in DR measurement, with an output signal at -60dBFS (or around 2mV), it shows.
I think that's the first time I see that.
About that: the use of 34dB Gain with APU did in fact mask the second harmonic, as you suggested... But gave me run after run, the exact same DR calculation for both channels.

Do they increase it on purpose ?
Well, my guess is that isn't intentional. Just a poor design and harware. Here was the WiiM Mini, supposedly, sharing the same chip (but probably slightly different implementation):
Wiim Mini Measurement Analog Streamer Android Bluetooth.png


For TIDAL usage, chrome cast Vs the Wiim app, any recommendations?
The one you like. I personally preferred the Tidal App through Tidal Connect. A bit more "snappy", and I've been familiar with the UI for years. Anyway, at the end I'm a Roon guy, so will honestly use pick that one over any other options. ;)

there is just one big precaution to take..
it is to realize that most of the observations in the digital domain on the digital outputs are dependent on the spdif input processing etc of your measuring device... here it is a strong processing which will level the results..
Sure, as with literally any analyzer on Earth, it may impact measurements... Yet, what exactly is the "strong processing" you're talking about ? Perhaps you missed that part:
REW FFT WiiM App.jpg

I don't think you can get any better than this when measuring a 24b/44.1kHz Sine, WAV generated by AP software (which BTW, is 997Hz rather than 1kHz), at... 0.00dBFS.
Here is what @amirm get with a APx555:
Wiim Mini Measurement Toslink Streamer Android Bluetooth.png

Does the AP S/PDIF input has a "strong processing" too?

That's really my only complaint (once they fix the auto-off behavior with optical input) - they should make it easier to switch sources. Ideally one should be able to do it from the "device" screen. Also on the "Browse" screen you should be able to put source selection on top.
Couldn't agree more ! I hope that @WiiM Support could consider the suggestion...;)

Spdif passthrough delay was 80 ms when measured by me and is 85 ms confirmed by WiiM support.
Yes, I read your posts in the product thread. I guess it's a "fair" delay. I did not bother at all while watching videos or gaming.

Minor Typo @VintageFlanker - ABC codec should be SBC codec I would imagine.
Thanks! Corrected. ;)
 
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