WiiM’s Pro Plus streamer – a tour de force

WiiM burst onto the scene recently with its Mini streamer, a small puck that connects to your network via WiFi. The analogue output from the internal DAC is so-so. The digital output sounds great when feeding a good DAC though, and the software is polished. All for £89 – hence it winning one of our 2022 Product of the Year awards.

Next came the £150 WiiM Pro, adding wired networking, a coax digital output and an optical digital input. Chromecast and Roon certification also bolstered its software credentials. Its sound quality was unchanged from the Wiim Mini, but for those needing the extra functionality the Pro is a great buy. 

Oh for a WiiM streamer with good sound quality on both digital and analogue outputs though. Step forward the WiiM Pro Plus, a Pro with a better DAC (and a remote control). At £220 it’s no longer impulse-purchase territory but it’s still good value. NAD’s similarly-endowed CS1 streamer got a big thumbs up when we reviewed it (here) for example, and that’s £300.

So, let’s put the Pro Plus through its paces. The NAD CS1 is still here, as is the WiiM Pro and my resident Pro-ject Stream Box S2 Ultra. Meaning direct comparisons are in order.

What you get

The Pro and Pro Plus are physically identical (I had to put a sticker on the Pro Plus to tell them apart).

On the back four RCA connectors cater for analogue input and output. There’s optical input and output, and a coax digital output. An RJ45 socket handles wired networking, with the USB-C input solely for power (meaning better 5V power supplies can be used). There’s a 12V trigger for switching on other equipment. And on the front are four touch sensitive buttons for volume up/down and play, plus a lone preset. 

Internally the DAC chip is upgraded from a TI Burr-Brown PCM5121 to an AKM4493SEQ, giving the Pro Plus up to 768kHz/32-bit PCM and DSD512 capability. DSD may be useful – it’s absent on the Pro. The increase from 384kHz to 768kHz PCM is academic to all but bats though.

Finally a simple remote – available separately for £20 with the Mini or Pro – is included with the Pro Plus. Four presets allow quick access to radio stations and the like. It allows voice control in conjunction with an external Alexa device. You can changes inputs or more to the next/previous track. I used it briefly for volume control, which was handy. 

Software

The Pro Plus uses the same Linkplay platform as the Mini and Pro – no surprise there, Linkplay is WiiM’s parent company. The Pro Plus is also going through Roon Ready certification as I write, hopefully that won’t take long (the Pro already has it).

Numerous music services are available in Linkplay, including Amazon Music, Deezer, Tunein, Qobuz, SoundCloud, Pandora, iHeartRadio, vTuner, Napster and Sound Machine. 

Tidal Connect and Spotify Connect are also present, as are AirPlay 2, Chromecast Audio, DLNA, Amazon Music Casting and Qplay 2.0 (that last one is new to me). All of which equates to a pretty comprehensive spec. Again, the WiiM app was very stable and responsive in use, and easy to navigate. It also looks good. The more I use it the more I like it. 

For a full comparison of the Pro and Pro Plus’ tech specs see here.

Listening

A Marantz PM6006 (£380) was used for initial listening as it has an inbuilt DAC, allowing easy comparison between digital and analogue outputs. Speakers were Graham LS6 standmounts (£2,400)

Initial impressions of the Pro Plus’ analogue output were very positive; that didn’t change. Take Steely Dan’s ‘Gaucho’, still a stonkingly good track both musically and sonically. Through the Pro Plus there was oodles of detail and a sizable soundstage. The prominent bass line was suitably tight, the opening saxophone raspy as it should be. Overall the sound was pleasingly full and lush, with a degree of swagger; it certainly carried you along. Messers Brecker and Fagen would have approved. 

Switching to the Pro Plus’ coax output through the Marantz DAC brought obvious changes. Clarity and precision replaced the more sensuous nature of the WiiM DAC. More detail was evident and the sound was tighter (the bass line had a distinct slap to it.) I get the feeling Becker and Fagen, with their meticulous attention to the recording process, would have approved even more. 

Me? I appreciated the fresher sound but ultimately found it ever so slightly relentless. It was trying tooo hard. The Pro Plus’ own DAC was marginally richer, more rounded. For me that was more persuasive musically.

Feelings reinforced by Maya de Vitry’s Infinite, an EP that’s turned me onto this singer songwriter big time. When her vocals arrived in the opening ‘Stacy, In Her Wedding Gown’ the Pro Plus’ own DAC had her sounding big and inviting. The Marantz DAC had her even larger, and more prominent. Impressive at first, but it also sounded artificial, almost overbearing. Give me the more relaxed rendition of the Pro Plus’ internal DAC any day.

But – and it’s a big but – those are my ears, my preferences. Some will side with the greater insight of the WiiM Pro’s digital output, and who am I to say they’re wrong? The key point is that the Pro Plus’ analogue output is now comparable to its digital one, it’s no longer a poor cousin. WiiM has delivered on what I imagine the design brief to have been.

Noting of course that the quality of the external DAC makes a big difference.  Connected to a £1,300 Mytek Liberty II the Pro Plus’ digital output was a distinct step up from either its internal DAC or the one in the Marantz amplifier. My listening notes from a session playing Anna Lapwood’s Midnight Sessions at the RAH showed I quite like it!

“Solid solid sound. Bloody glorious. The slightly dry, digital nature of the WiiM suits the swelling organ beautifully, keeping it in check. Just magnificent. Who needs a wetter sound anyway?! I don’t let rip on the volume often. Tonight I did.”

Versus the WiiM Pro

So in isolation the Pro Plus sounds great, but is it a worthwhile step up from its sibling?

Playing the Pro Plus and Pro’s digital outputs into the Mytek Liberty II (now feeding a £6,500 Prima Luna EVO 300H amplifier) showed no differences between them. Which is what I expected but it was good to have it confirmed.

Onto the analogue outputs, where I thought the better DAC of the Pro Plus would easily best the Pro. Listening showed that, yes, the Pro Plus was better. At first it wasn’t the knockout win I was expecting though. Doubts began to surface. Had I dissed the Pro’s internal DAC too harshly in its review. Cue numerous tracks to highlight specific aspects of performance – bass, treble, soundstaging etc. 

And slowly but very surely clear differences became apparent. Overall the Pro was distinctly softer than the Pro Plus. Dynamics in particular were muted in comparison. 

Secret Machine’s ‘First Wave Intact’ (from Now Here Is Lonely) sounded rather muffled through the Pro. Switching to the Pro Plus the sound burst from the speakers, catching me unawares even though I knew it was coming. That was better. The Pro Plus also gave the guitars more bite thanks to greater top-end extension. The sound was altogether more open. 

Returning to the Pro, Maya de Vitry sounded perfectly nice, everything in place, nothing offending the ears. It was all a bit polite though. Switching to the Pro Plus brought more air and more detail. The sound was just more engaging. That a £220 streamer’s own DAC could sound so good through the expensive Prima Luna amplifier was very impressive.

The WiiM (bottom) and the NAD (top) have similar connectivity

Versus the NAD CS1

So in isolation the WiiM Pro Plus is a success. No ifs, no buts. What if we go outside the WiiM stable? 

Out came the NAD CS1, at £300 a sensible comparison. Unlike the WiiMs it’s a bare-bones streamer, dependent on the music services you use to control it (BluOS is the reserve of more expensive equipment.) But the CS1’s sound quality proved excellent at its price level when we reviewed it. Game on. 

And actually,  on analogue output it was game over pretty quickly. Using their internal DACs the Pro Plus and the CS1 sounded near as damn identical. Maybe there was a tad more extension to the CS1’s treble, but I’m not sure I’d spot it in a blind test. And that was listening through £10k of amplifier and speakers. Both sounded very good indeed; I could live with either. 

On digital outputs I was expecting the same outcome, after all, bits are bits aren’t they? Apparently not. Playing through the Mytek Liberty II the Pro Plus was marginally better than the CS1. Treble was more extended, generally the sound was a little tidier. Not hugely so but noticeable to these ears at least. 

Then bells started ringing, so I checked out my review of the NAD CS1 again. I’d compared its digital output to that of the WiiM Pro and reached the same conclusion; the Pro’s digital output was marginally better than the CS1’s. And we’ve just found the digital outputs of the Pro and Pro Plus sound identical. No surprise then that the Pro Plus’ digital output bests the CS1’s slightly. Consistency, don’t you just love it!

So overall the Pro Plus wins the sonic contest with the CS1 by dint of a slightly better digital output. The differences are marginal though, to these ears not something I’d worry about in a starter system. Both devices show themselves to be excellent performers.

Mytek’s Liberty II DAC

Versus Pro-ject’s Stream Box S2 Ultra

My go-to streamer is Pro-ject’s little Stream Box S2 Ultra – a mouthful of a name, a tiny box that consistently sounds excellent. At £629 it’s twice the price of the excellent Pro Plus (with upgraded power supply). Has the Pro-ject’s time come?

It only has one digital output on USB, rather than the coax & optical of the Pro Plus. So we’re not quite comparing apples with apples, but it’s pretty close playing both through the Mytek Liberty II.  

Listening to them consecutively was fascinating, the similarities outweighing the differences. Ultimately the Stream Box S2 Ultra emerged on top courtesy of a cleaner sound and more extended treble. Greater detail emerged and there was more zip to the sound. The horn section on George Benson’s ‘Give Me The Night’ was more distinct on the Pro-ject for example, the Pro Plus more muted in comparison. The orchestral strings were further forward in the mix too. Complexity favoured the Pro-ject, which unpacked it better. 

As with many soundtracks, Alva Noto’s ‘Kinder Der Sonne (Intro)’ is built on a foundation of low low bass that rumbles atmospherically around the room. Through the Pro-ject it had more authority, greater menace than the Pro Plus. It was also more distinct, easier to hear, as were the other layers of the mix. The Pro Plus homogenised the sound slightly, bleeding the different elements together. 

In the context of a £10k system those differences matter. Much less with Hifi Starter systems though. The surprise was how close the Pro Plus’ coax output got to the sound of the Stream Box S2 Ultra. It was a slightly sobering exercise.

Summary

So for £220 we have a discrete streamer that sounds great. The Linkplay software is a joy to use. And a good external power supply such as iFi’s £69 iPower 2 squeezes even better performance from it.

Suitably attired, playing through my Mytek Liberty 2, the Pro Plus didn’t just hold its own in a £12k system, it positively soared.