After many months of trial and error, fun, heated discussion, lots of parts swap and of course music listening, the SGM 2015 network player was ready to debut during the 2016 HighEnd Show in Munich where Geoff and team had arranged a demo in the BMW headquarters [below]. Next to many representatives of the online audio community, the audio press and of course the full SGM music server team, the team's software collaborators were present as well - HQPlayer developer Jussi Laako and Roon's Enno Vandemeer. For a report on that gathering see here for more. That demonstration back then was very convincing in the sense that we thought the design team had chosen the right path to pursue for their subsequent R&D. For a long time we'd already lived with a custom-built fully tweaked-out Windows PC running XXHighEnd in combination with the Phasure NOS1 DAC. This software/hardware combo does all the processing prior to sending PCM data to the DAC. When you select an album to play, you must wait up to a few minutes before the music starts. Under the covers, the software spreads the processing over all available CPU cores (the actual processing engines), hence the more cores, the faster the processing. The resultant sound is very satisfactory but the way to arrive there is a real pain in the ass. XXHighEnd has so many settings that identifying the most optimal is a life-time job.

Another PC-based audio streamer we have experience with is the Pink Faun. They use a fully passive solution for cooling and JRiver as the streamer's software. Next to being passively cooled, the Pink Faun is fully equipped with high-grade power supplies dedicated to each individual part and the best OCXO clocks to reduce jitter. Just like with the XXHighEnd PC, the underlying Windows operating system is stripped down to the bare bones to reduce processing overhead and potential noise. This streamer too operates in full PCM mode. For their SGM 2015, Sound Galleries too went after passive cooling, including equipping each memory bank with its own heat sink. All this cooling is necessary because the SGM 2015 is designed to do its intense computation in real time. When highest audio quality is key, HQPlayer converts all incoming signal to DSD512. If no DSD DAC is available, the software is equally happy to output high-quality PCM which moves a lot of processing onto the DAC. A true DSD converter is really just a low-pass filter. All the heavy computations to arrive at a high DSD signal are, in this case, already done by the streamer.

HQPlayer offers a wide range of resampling filters which can be a bit overwhelming for the first-time user. What re/oversampling filter to go with: IIR, FIR, asymFIR, minphaseFIR or FFT, poly-sic, poly-sinc-mp, poly-sinc-shrt, the poly-sinc-shrt-mp or one of ten others? Then there are the noise shapers cum dither modulators. Here one may choose from 16 different settings, some with specific benefits for certain DAC chips. Mind you, one can instead also set the defaults for PCM and DSD together with the desired sample/bit rate for either. Because Windows is the operating system, one needs the correct driver for the DAC to be used. About drivers, the Mac OS is much cleverer but here one must deal with the quirks of Windows. All these settings and computer-based optimizations might seem difficult or cumbersome but we will see later that there is a user-friendly way to deal with them.

Normally, setting the filter, noise shaper and installing the driver is a one-time job. After that the user interface is the only thing that sits between music and listener. Sound Galleries' chosen GUI is Roon and we fully applaud that choice. It works like a punctual German train on nearly all platforms, organizes your music library and offers an ideal interface with Tidal and Internet radio stations. On top of that, Roon adds extra information about the music and artists just like a virtual record sleeve with liner notes.

Even though here the Windows 10 Home installation is stripped of all unnecessary and potentially interfering processes and services, the heart of the operating system still remains active. That has its own way of steering the goings-on. This OS is the server's conductor and points its baton at the task to be performed which is then executed in the CPU, the central processing unit. In the SGM 2015, that CPU is an Intel quad-core i7 6700K running at 4.2GHz. Quad core means that the CPU is in fact 4 CPUs packed together to share common things like power/memory access. You might thus assume that such a CPU can do four things more or less simultaneously. Actually, these types of CPU can do eight things at a time due to a technique called hyper-threading. On top of that, tasks/threads can be spread out over the cores such that otherwise idling cores jump in to avoid unnecessarily waiting threads. Intel even offer a Turbospeed option for the CPU to run one core at a higher clock speed over a limited time. Emile tweaked this feature so that all the CPU cores run at that 4.2GHz Turbospeed all of the time as long as HQPlayer is active.

As mentioned, the Windows conductor has a bit of its own mind to assign priorities to certain tasks. From an operating system perspective that's grand but not for a demanding audiophile application like HQPlayer. Roon too is demanding in its CPU-loading behaviour. HQPlayer wants things done in real time and Roon wants quick responses as well. The Sound Galleries team learnt that this caused too many priority conflicts, hence audio degradation when Windows control was allowed to operate in standard fashion. Enter Process Lasso Pro [below]. This piece of add-on software handles thread schedules over the available CPU cores more intelligently and purpose-specific than the Windows default. Now settings can be tailored for specific uses. For their HQPlayer + Roon rivalry, the Sound Galleries team dedicated two CPU cores to Roon, six to HQPlayer. Both applications are multi-threaded to where Roon and HQPlayer run over 100 joint threads.

We had our review samples of SGM 2015 servers and T+A DAC 8 hand-delivered by Geoff Armstrong and Emile Bok. Edward Hsu had other business to take care of. With dimensions of 48x43X17cm, their music server is sized like a full desktop computer but its weight of 35kg has mainframe aspirations. Because we don't own a DSD512-capable DAC, the T+A became part of our loaner care package. Sound Galleries deliver all of their SGM music servers preinstalled to the customer with all the required software including drivers for the user's DAC. Furthermore, Sound Galleries offer a remote trouble shooting and upgrade service. Should a user run into trouble of any kind, a member of the SGM team can, with the user's permission, access the server via TeamViewer remotely, install a new driver when a different DAC is to be used, aid in selecting the best settings for HQPlayer and solve any other issues. This bespoke service comes as a subscription.