Network Audio Players/Servers

It’s also worth noting that when it comes to network streaming, the S2 Ultra is format-transparent, provided the networking you’re using has enough bandwidth to handle the data-rate – which is one reason I tend to stick to wired connections whenever possible. After all, it’s ‘simply’ taking in data and outputting it via USB, so the format range that can be played is down to the capabilities of the DAC connected to the ‘audio-optimised’ USB-A output, not the S2 Ultra itself. The same goes when playing music from USB storage devices connected to either the front or rear USB-A ports.

Compare And Contrast
As I have noted with similar, if rather more expensive, ‘bridge’ devices in the past, the sound is almost entirely dependent on the abilities of the DAC with which it’s used. That means the best one can do is consider how it compares with the performance of the same DAC(s) connected to alternative means of achieving the same end, typically some kind of computer hooked directly into the DAC. Alternatively, one needs to compare the box plus a given DAC to more conventional all-in-one network players, which take a network connection and output analogue audio.

Let’s begin with its ‘bonus’ role as a USB ‘detoxer’, something that Westlake has been working on for some time. In every combination I tried – from various Macs connected to the USB-B inputs on the likes of iFi Audio’s Pro iDSD [HFN Sep ’18] and the Quad Artera Solus [HFN Jun ’18] through to a Raspberry Pi as player into a Chord Mojo [HFN Jan ’16] and Meridian Explorer2 – the S2 Ultra’s pass-through USB ‘cleaner’ revealed more detail in the sound, and greater weight and definition in the bass.

That meant more of a grumble and a sense of strings vibrating in Marcus Miller’s playing throughout Laid Black [Blue Note 8002850802; 48kHz/24-bit], underpinning the music more convincingly. It also projected a better sense of the weight and punch of the drums on the march from ‘1941’ on the Dallas Winds’ latest set for Reference Recordings’ John Williams At The Movies [RR-142; 176.4kHz/24-bit]. That makes this outlandishly dynamic recording even more dramatic and thrilling, and the impact of the snares, not to mention the textures within the woodwind and brass, are even better delineated, even when the band is working hard.

DIY Options
Mentioning the Raspberry Pi back there reinforces the general difficulties of reviewing the Stream Box S2 Ultra on anything other than purely functional grounds. I had a Pi, a Tinkerboard and an Intel NUC to hand during this test as ‘sources’ to compare with Pro-Ject’s solution as a network audio transport, along with a battery of ‘USB improvement’ devices including Audioquest’s Jitterbug, iFi Audio’s iPurifier and Ideon Audio’s 3R USB Renaissance.

Each combination has its own sound, even before you take into account the DAC that’s used, and I came out of what was virtually an all-night session of listening and switching convinced that almost any of these combinations were on a par with the S2 Ultra for less – in the case of a Pi and iFi Audio – or not much more (NUC and Ideon). However, taking stock in the cold light of day, I began to appreciate just what this little silver all-in-one box could do as a transport into most of the DACs I tried.

Diddy though it is, the S2 Ultra still needs adequate ventilation. I found the casework got noticeably hot to the touch, possibly too hot during the 30oC+ peaks of the UK summer this year, and this coincided with a few audible dropouts and the power light flashing red and blue.Powering down and up again – by removing the plug from the mains supply – seemed to resolve matters.

That minor glitch aside from what was clearly an early production sample, I must say that the S2 Ultra worked seamlessly with all the USB-capable DACs I had to hand, and made it very simple to access both network- or USB-stored music and online services.

Yes, you could do much the same with a bit of mini-computer assembly, downloading of software, installation and set-up, but rather as with the much more expensive Roon Nucleus+ [HFN May ’18], the beauty here is that all the work is done for you, and you can just plug in the unit and be listening almost instantly.

High-End Too!
That’s the true appeal of this little box, and I must admit I had a most enjoyable time playing a wide range of music via the S2 Ultra into all kinds of DACs. I even used my Naim NDS as a converter via the Mutec MC-3+ Smart Clock USB [HFN Feb ’17], which I guess means the output into the DAC was double-detoxed!

The S2 Ultra performed well: streaming was smooth and glitch-free, even if the app/box combination could be a little peppier in its reactions, and it simply gets on and lets your chosen DAC do its thing to the best of its abilities. For that alone, it’s a perfect choice for anyone new to streaming audio.

Hi-Fi News Verdict
The sound quality rating here is somewhat arbitrary, and simply reflects how well this little Pro-Ject box compares to the use of a DIY solution, and its secondary ability when it comes to cleaning up the sound of USB audio from a computer. Yes, there are other ways of doing that if you are prepared to put in some effort, but the Stream Box S2 Ultra makes very light work of adding streaming to your system.