Media Server Reviews

Characteristically, the email from Kal Rubinson got straight to the point: "I have a WiiM Mini that I have played with, but I am not the right one to review this as I am not sufficiently interested in or knowledgeable about wireless streaming. It ... can handle uncompressed PCM via its DACs." "I'll review it," I replied, intrigued by a $99 D/A processor that can stream hi-rez audio via Wi-Fi and that also has an analog input so it can act as a preamplifier. Functionally, the Mini resembles the Lumin P1 that I reviewed in the April 2022 issue but at a tiny fraction of the Lumin's price. I was particularly interested in using the WiiM streamer as a network bridge with legacy D/A processors that don't have a network or USB port, such as the Mark Levinson No.30.6 I bought in the 1990s.

The Mini
The WiiM Mini is a tiny, circular device just 1" high, made by Linkplay Technology. The top has three capacitive touch icons—Play/Pause, Volume Up, and Volume Down—and a multicolor LED that indicates basic functional status and activity. It flashes white quickly when the Mini is booting up and slowly when it is ready to be set up; it flashes green quickly when it is connecting to a Wi-Fi network and slowly when it is ready to pair with Bluetooth. When the Mini is connected to a Wi-Fi network, the LED glows solid white. Around the side of this circular device are an auxiliary two-channel analog input on a 3.5mm stereo jack, a two-channel analog output, also on a 3.5mm stereo jack, a USB-C port for connecting the supplied 5V power supply, a TosLink optical S/PDIF output, and a tiny hole covering a microphone that WiiM says is "AMIC for AirPlay 2 sync." That's all there is to see. The Mini's outer simplicity, though, belies a wealth of features. "Turn any audio gear smart" is printed on the user guide cover.

Audio files up to 16/48 can be streamed to the Mini via AirPlay 2, but hi-rez audio up to 24/192 can be streamed to it via Wi-Fi with the WiiM Home app. The app supports Spotify, Tidal, Qobuz, Deezer, Amazon, and many other streaming services, and it features Gapless playback. Moreover, it can stream the same audio to multiple Minis to allow wireless multiroom operation. A Sync function in the setup menu allows the different latencies of the multiple Minis to be compensated for, using the Mini's own microphone. Amazon's Alexa and Apple's Siri can be used for voice control.

An adaptive EQ feature offers not just the usual loudness, treble, and bass controls but also settings for 13 specific types of music as well as one to compensate for small speakers. The user manual describes this feature aptly: "When adaptive EQ is enabled, the music genre information and other tags included in the audio content are used to adjust the frequency in real time—either bringing rich audio to capture every music detail or making human voice clearer in the podcast."

When selecting the analog input, the Mini's top-panel LED glows green, and it converts the analog signal to a 16/48 digital signal. The digitized data can then be directed either to the optical S/PDIF output or to the analog output, where it is converted back to analog with a Burr-Brown PCM5121 DAC chip. (When a 3.5mm plug is inserted into the analog output jack, the digital output is disabled.)

Setup and headphone listening
Setting up the WiiM Mini was a painless process. I installed the WiiM Home app on my iPhone 11, paired the iPhone with the Mini via Bluetooth, and followed the app's instructions. Using the app, I logged the Mini into my 5G Wi-Fi network, and once the Mini had updated its firmware (to version 4.6.412161), I entered my login info for Qobuz Studio (24/192) and Tidal. I activated the Mini as an AirPlay 2 device in Roon and was able to connect to it with AirPlay. I was also able to stream YouTube soundtracks to the Mini via AirPlay 2.

I was ready to play AIFF files from my iPhone and iPad music library and found that I couldn't. The manual set me straight on that one: AIFF-C file playback is not supported.

As the Mini's analog outputs have a relatively low source impedance—see the Measurements sidebar—I started by using my high-impedance Sennheiser HD 650 headphones. I first fed audio to the Mini's analog input. I didn't try the Adaptive EQ, as I was interested in the Mini's intrinsic sound quality.

Inspired by Tony Scherman's article on Bonnie Raitt in the June 2022 issue of Stereophile, I streamed her new album, Just Like That ... (26/96 FLAC, Redwing Music/Qobuz), to a Mytek Brooklyn D/A processor from Roon via USB and fed the DAC's single-ended output to the Mini's analog input. I had to set the Brooklyn's volume control relatively low to avoid distortion on peaks. The lows sounded soft and the highs somewhat grainy, but considering that the signal was undergoing successive D/A, A/D, and D/A conversions, the Mini was more listenable than I had expected.

Next, I streamed the Bonnie Raitt album to the Mini from Roon using AirPlay 2. There was now more air in the presentation than when I used the analog input, though the bass was still softened. But, as AirPlay downsamples the original hi-rez audio, I streamed the album from Qobuz at 24/96 audio, using WiiM Home. The bass now had more subjective extension and leading-edge definition. I next selected the Mini's TosLink output and connected it to the Mytek Brooklyn, so I could listen with my reference Audeze LCD-X headphones. That's when I ran into problems.

Problems
The app allows the Mini's S/PDIF output to be set to 16- or 24-bit resolution and to maximum sample rates of 48kHz, 96kHz, or 192kHz. With the S/PDIF output set to 24 bits and 192kHz, I could play 24/96 and 24/192 files from Qobuz with full resolution and bandwidth. However, when I set the S/PDIF output to 24 bits and 96kHz, 24/96 Qobuz files were downsampled to 16 bits and 44.1kHz. If I then reset the S/PDIF rate to 192kHz, the 24/96 files were still downsampled. (I made sure that the Qobuz interface in the WiiM Home app was set to allow "HiRes up to 192kHz"; this was confirmed by WiiM as a firmware bug, which they promised to fix in their next update.)

Power cycling the WiiM Mini solved this problem—except that it recurred when I tried playing a 24/48 Qobuz file after playing a 24/96 file. The problem was still there when I then played 24-bit WAV files from my iPad: They were truncated to 16-bit resolution until I power-cycled the WiiM Mini again. (I determined sample rate and active bit depth using my Audio Precision's digital-input analyzer.)

There was either some hardware problem with my sample or, more likely, a firmware issue. Editor Jim Austin asked Linkplay's Linda Kim to send me a new sample; she sent two in case I wanted to try the Mini's multiroom capability. (I didn't test this, however.) I unpacked one of them, powered it up after installing the latest version of the WiiM Home app on my iPad, and logged it into my 5G Wi-Fi network. As I expected, the Mini updated its firmware—this time to a newer version (4.6.415357), dated April 29, 2022. I made sure that the app's Qobuz account was set up to allow hi-rez playback, set the TosLink output to handle data up to 24/192, selected the Bonnie Raitt album, and pressed Play.

Problem-free listening
All was well. The Mini's analog output reproduced Bonnie Raitt with the same overall quality that I had experienced with the first sample of the Mini, but now the TosLink output carried 24/96 data. Next up was "Don Juan," a track from the June 2022 issue's Recording of the Month—a collection of works by Richard Strauss conducted by Andris Nelsons (24/96 FLAC, DG/Qobuz). The orchestral sound was lush, and I couldn't hear any difference between the signal fed to the Mytek via Wi-Fi from the WiiM Mini or via USB from Roon.

The Mini as a network bridge
I retrieved my Mark Levinson No.30.6 from storage and connected the Mini's TosLink output to one of its TosLink inputs. Since the Levinson can't accept S/PDIF data sampled at 192kHz, I used the WiiM Home app to set the Mini's S/PDIF output resolution to 24 bits and 96kHz. And as it doesn't have a volume control, I set the Mini's output to variable volume so I could connect the No.30.6 directly to the Parasound monoblock amplifiers.

I first connected the Mini's TosLink output to the Mytek Brooklyn, to make sure all was working correctly. With the Mini's S/PDIF output set to 24/96, Bonnie Raitt played with the correct resolution and sample rate. However, while Jackson Browne's classic Running on Empty (24/192 FLAC, Asylum Records/Qobuz) was downsampled to 96kHz as expected, the word length (as revealed by the Mytek's display) was reduced to 16 bits. This truncation will likely be addressed in the next firmware update (see Postscript), but for now, I stuck with files sampled at 96kHz or lower for playback with the Levinson.

I had forgotten with how much drive and low-frequency authority the No.30.6 endowed playback. But compared with my current digital reference, the MBL N31, the soundstage had somewhat less depth; the highs a touch more grain. Even so, the WiiM Mini dragged the Levinson DAC into the 21st century.

Conclusion
The WiiM Mini's analog input and output are serviceable, but it's the ability to output hi-rez audio data from its TosLink output that gets this bargain-priced product a recommendation from me. But to ensure bit-perfect playback, unless you are using a D/A processor that is restricted to sample rates of 96kHz or lower, be sure to set the Mini's S/PDIF output to 24/192. And to make sure the device is working at its best, be sure to download the latest firmware update.

Postscript
Some weeks after this issue's content had been sent to the printer, I set up one of the Wiim Mini samples and updated its firmware to the most-recent version, 4.6.42.1831, dated 20220701. Now, when I played hi-rez files from my iPhone or streamed 24/96 and 24/192 audio from Qobuz, the problems I found with word-length truncation when I changed the maximum S/PDIF sample rate no longer happened.