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WiiM Pro Plus - Review & Measurements (Streamer)

VintageFlanker

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WiiM Pro Plus - Review & Measurements

Main.jpg

Hi Folks,

Here is another review, measurements-based, today about the WiiM Pro Plus (or "Pro+"). While some rumors already mentioned it for the last couple of months, it is just launched today (August 8) officially. The WiiM Pro Plus comes with a $220 MSRP (planned to be 249€ in EU), so quite a price jump from the original WiiM Pro ($149/179€), that is still less than one year old. The unit I got is a preproduction sample, that has been sent to me directly by WiiM, after they contacted me for evaluating their new product, which of course I accepted.

To ruin the suspense, the WiiM Pro Plus is nothing but a WiiM Pro, with just an upgraded DAC (and ADC). When I reviewed the WiiM Pro, I gave it my recommendation considering the serious amount of features, the excellent digital performance and a decent app and ecosystem. Regarding analog circuit design, tho, the performance was nothing better than mediocre. The Pro Plus now comes with new OPAMPS and an AKM AK4493SEQ chip, which is claimed to be a significant upgrade over the TI (PCM5121?) DAC that we often see in Streamers in this price range. That, we will verify.

Note: These measurements will be mainly focused on the supposed improvements brought by the Pro Plus over the regular Pro, so specifically on the DAC performance. For any other analysis of features and connectivity, please read my review of the WiiM Pro here.

Note: Because the preproduction unit I got from WiiM came with a lot of scratches and molding marks, it would not have been a great subject for my type of photography. This time, I will then post promotional pictures (except for the very shady one above) instead. Edit November 2023 : new picture from the final production sample added.​

Front.jpg


As you may see, the Pro Plus is virtually indistinguishable from the original Pro. The chassis is exactly the same, as are the outputs and inputs. The main difference is that the Pro Plus comes with a glossy black coating, instead of the greyish color of the Pro. I honestly do not like this finish at all. It will be either a fingerprint or a dust magnet, in addition to be sensitive to scratches. The biggest (really, the only) addition, is that the WiiM Remote is now supplied. This one actually retails separately for $20 (and is hardly available anywhere in Europe !), so it sure is a very cool adding.

One last thing, though: While we waited months for the WiiM Pro to finally get its Roon Ready certification, the Pro Plus is still not certified as of this writing. I assume that this will be updated anytime soon and that Roon is working on it at some point.​
Back.jpg

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 : RME ADI-2/4 PRO SE. E1DA Cosmos ADC (Grade B), Minimum phase filter. 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 1.0.87 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.

Note: Prior to this publication, I showed my measurements to WiiM.

Edit November 2023 : Few weeks after this review, WiiM sent me another WiiM Pro Plus. The latter happens to be a final production sample (meaning the same that you can actually buy). I measured waited quite a few time to re-measure this final sample. I will update some graph showing the improvements over the preproduction unit I got back in July.

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WiiM Pro Plus - DAC Summary
Tests
Manufacturer's specs
Results (L & R)
Preproduction sample
Results (L & R)
Final sample
Rating
Noise Level (REW)​
/​
-122.5dBA​
Stellar
Dynamic Range (REW)​
120dBA​
119.3dB​
Excellent
THD (REW)​
/​
0.00022%​
Very Good
THD+Noise / SINAD (REW)
-108dB
-111.6dB
-115.2dB (-116.1dB with Cosmos Scaler)​
Excellent
IMD SMPTE (REW)​
/​
-92.3dB​
-104.6dB
Good / Very Good
Stereo crosstalk (RMAA)​
/​
-119.2dB​
Excellent
IMD+Noise @10 kHz (RMAA)​
/​
0.00039%​
Excellent
Multitone 32 TD+N (Multitone)​
/​
-105.1dB​
Excellent

Total Harmonic Distortion + Noise (SINAD) - 24b/44.1kHz
REW THD+N R.111.9.png

Edit November 2023 : Now, the production sample, also measured with Cosmos Scaler:
REW THD+N Scaler.png

Definitely an improvement, even if it should not be audible.

Frequency Response - 24b/44.1kHz
REW FR.png


Noise Level - 24b/44.1kHz
REW NOISE.png


Dynamic Range - 24b/44.1kHz
REW DR.png


Intermodulation Distortion SMPTE - 24b/44.1kHz
REW IMD SMPTE R.92.2.png

Edit November 2023 : Final production sample:
REW IMD SMPTE.png



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

Edit November 2023 : Final production sample:
IMD SMPTE VS Level.png


THD Versus Frequency - 24b/48kHz
THD VS Frequency.png

Edit November 2023 : Final production sample:
THD VS Frequency3.png


Jitter - 24b/48kHz
Jitter.png


Multitone 32 - 24b/192kHz

Multitone 32.png


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

imdswept.png


Crosstalk - 24b/44.1kHz

cross.png

Long story short: the Pro Plus absolutely wipe the floor with the regular Pro. Starting with a SINAD better by 24dB. It nails almost every test, except for the IMD SMPTE one, that is not exactly showing the textbook perfect behavior I would expect for the AK4493. I measured better from other implementation of this chip in this very scenario. Obviously, it also impacts the SMPTE VS Level test: While not showing the "Hump" we often see with some ESS DACs, it should go down to about -110dB before rising at full output. Otherwise, it just performs great. Period.

Note: For repeatability purpose, you may also check the (very extensive) measurements provided by @onlyoneme at the WiiM forum. Both our results essentially match, assuming we use different methodology and hardware.​


ADC Performance
For these few tests I initially did not have any reference DAC for tone generator on hands, before I receive the S.M.S.L C100, that I will review in the future. The latter, showing about 115dB SINAD at full output (2.083Vrms), is certainly good enough to provide a reference signal in order to measure the WiiM Pro Plus ADC performance. Lowering the volume down to -4 (1.50Vrms), I got about 105dB SINAD and also used this to test the analog inputs.

Total Harmonic Distortion + Noise (SINAD) - 24b/44.1kHz
ADC REW THD.png

The first observable modification, before any measurements, is about the sampling frequency. The ADC is now set at 192kHz, instead of 48kHz before. Fortunately, the signal remains very stable through whatever Toslink or Coax output. About the results, you can already note that some progress have been made on that field. Sure, THD+N is very similar to the regular Pro's analog input. But it can now carry a stronger signal (original Pro started to clipp at 1.20V). It is now usable to be feed by more sources.

Then, about the absolute limits of the ADC input:​

Total Harmonic Distortion + Noise (SINAD) - 24b/44.1kHz
ADC MAX.png

It now may go way higher, until 2V, whereas the performance is degrading. Passing 2V (and reaching full output of the C100 DAC), the ADC is finally clipping, which is a bummer. We still cannot rely on it for many sources, such as >2Vrms CD Players without variable output. Like the original pro, tho, this level of performance will be perfectly suitable for the Pro Plus to be fed by a phono/turntable signal.

Note: For further investigation about the ADC performance, I again recommend checking the second part of measurements from @onlyoneme posted at WiiM forum.


Conclusions

I will be very short this time: The WiiM Pro Plus fixes most of the downsides of the original Pro, the biggest being the overall, and initially unremarkable, analog performance. It is now possibly one of the best measuring standalone streamer out there, and certainly the best at that price point for now (Yes, I do not consider the Allo Boss2 as a standalone streamer). Every quality I praised about the WiiM Pro are now adding to objectively excellent D/A abilities. The ADC, on the other hand, still leaves to be desired. While now being able to handle higher level inputs, which really was a deal-breaker for using the analog inputs of the regular Pro, WiiM should have been more precautious with some extra input allowed for more sources. Putting this aside (and having personally no need for it), I will give the WiiM Pro Plus my recommendation. At $220, with the remote included, and without the need of adding an external DAC (at all), it is nothing but a bargain.

Flanker Rating: Very Good
 
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Kachda

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Quite good. But for those with a good DAC ultimately not required if they already have the pro.

@VintageFlanker Does it use the same processor? Today we learnt that the PEQ only has 4 bands on wiim pro, probably limited by processor power. At $100 more, it should ideally have more processing power and therefore peq bands than the pro.
 

kemmler3D

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Nice review and congrats on getting to "preproduction sample-worthy reviewer" status with them.

Looks like this saves anyone with remotely normal expectations for their DAC / ADC from the trouble of buying outboard units for those functions. Looks like the era of flexible, good-quality, and affordable whole-house streaming is here, if you don't want to buy into the SONOS ecosystem. It was a long time coming!
 

Tangband

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I believe this deserves the golfing/soccer panther ASR award.
Yes it does :)

I even like that this streamer is black - looks like an Apple TV.
 
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morillon

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your choice of scale hides the order of magnitude but the distortion is really sensitive under 1k...(the smpte shows it well)...
but as I said on the wiim forum, it may just be due to the filter embarked among a long choice proposed by akm it seems...?
will just be to check if that or not, but will it be possible in the future to have access to the proposed filters or the frozen situation...?
(akm could be able to provide some data on this point?)

mesureament from

Thread 'My WiiM Pro Plus (+) tests' https://forum.wiimhome.com/threads/my-wiim-pro-plus-tests.1235/
 

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morillon

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however.. time passes.. and no one of the people with access to these betas has dared to take his pen too much to give his feeling on the listening side, see a comparison of anothers solutions etc
¿?¿?
;-))
 
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Brantome

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Glad the unit finally got to you and you had a chance to test it :)

Re Roon Ready, WiiM said “We expect the Pro Plus will be Roon Ready in a couple of weeks since it won't need to go through the full certification”.
 

Jeromeof

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