With their two team members in the house, they performed the initial setup and made sure things were peachy. For remote control, one can run a Roon Client and remote access tool like RealVNC or TeamViewer from an iPad or telephone. Our resident iPad was an older 32-bit model and Emile offered to send a more current model. With the SGM/DAC combination playing in the background, we had lunch and talked all things music and life. The next day we had a closer look at the SGM 2015. After releasing the 12 bolts that hold the heavy lid in place, we had a clear vision of the innards of this remarkable product. In the left back the eye catcher was a huge steel-clad toroidal power transformer plus two oversized chokes. This large power supply is necessary because the CPU exhibits rather erratic power-hungry behaviour when fully loaded down by heavy computation. Power must be available and delivered quickly at all times. Noise is the biggest enemy of good sound and keeping it out from the start is the task of the big chokes. A large custom CNC'd aluminium heat sink keeps the parts on this side of the server nicely cool.


At the right of the power supply sits a heavily modified Asus Z170M-Plus PC motherboard. The main attraction here was the passive cooling system for the Intel i7 6700K processor running at 4GHz to not be overclocked. Heat pipes transfer CPU temps to the right fanned heat sink which unlike the left aluminium sink is of custom-machined copper. In their tests, the team saw that a massive copper heat sink was much faster at conducting heat away from the heat pipes and dissipating it further into the room which the music server operates in. Even more heat-dissipation functions are applied to the DDR4 random memory modules totaling 16GB. Team SGM found that applying a heavy aluminium strip to both sides of each memory module not only kept the module cool, it improved sound quality.


Clock accuracy for real-time apps is another noise/distortion generator that should be eradicated from the very beginning. For that purpose a high-precision OCXO oscillator replaced the stock Asus clock. That is located at the divider between the power supply's transformer and motherboard. Connor-Winfield supplied the 24MHz master clock whose 5ppb stability is far lower than competitors. Stability is a factor over time, hence this clock is more stable over longer periods. That is different from accuracy which is measured over far shorter bursts of time. According to Emile, this 5 parts per billion oscillator is more accurate than versions with a higher stability rating and therefore their clock of choice. Another mod to the motherboard is its power supply. In fact, Emile Bok's own company Taiko Audio here contributed two separate regulated supplies on an OEM basis. One of these power supplies is dedicated to the 1TB solid-state hard disk, the other is for the OXCO clock. Under the power supply boards sit a bundle of Mundorf Mlytic capacitors with 660'000μF of storage capacity. In later builds of the SGM 2015, even the solid-state disk gained an aluminium cooling plate for which we received the upgrade even though our photos still show the bare disk. At the back of the SGM 2015 its i/o, from left to right, include the PS/2 style keyboard and mouse connectors, one DVI-D and one D-Sub video output, an HDMI port, a mini USB port, two USB 3.0 and 2 USB 2.0 ports, the LAN RJ45 port and 3 audio jacks. At the far right there are the IEC terminal, the AC fuse and the main power switch. At the front there's only one switch, a white LED-illuminated boot/shutdown button.


Now for the software. As already mentioned, the SGM 2015 runs Windows 10 Home in a stripped-down version. Unneeded services and other overhead are disabled or removed just like the page file. The system runs everything in real not virtual memory. On top of the OS there's just Process Lasso, HQPlayer, Roon and the VNC remote access server. The other kind of software became our music. Through the USB 3.0 ports, we connected our music library of WAV/Flac files stored on 3TB USB disks. Once connected, Roon automatically indexed the files and made them accessible through its interface. It was just as easy to link Roon and Tidal so that a wealth of new Flac files became available including our favorites list. For some reason Qobuz is not Roon ready and it seems that the French are not likely to join. For those who want to access their hi-res and other files via the Qobuz streaming services, there is the freeware Kodi player interfacing between Qobuz on a separate PC or Mac; or on the SGM 2015 locally.


It seems to us that all music server software, HQPlayer included, must have some quirk or oddity as a matter of pride. In HQPlayer's case it is the fact that all filters get assembled in memory and are not ready to roll already stored on a disk. This means that each time HQPlayer launches after the system boots up, there is a delay of up to half a minute during which the chosen default filter gets constructed. Rumour has it that's how Jussi protects his filter algorithms. Also when switching from let's say PCM 16/44 to 24/96 files, HQPlayer must do some calculations. It is thus recommended to group playlists on file formats or take the delay for granted. During our time with the SGM and T+A DAC 8, we had also the privilege to review the LampizatOr Atlantic DAC. Like the T+A, that Polish converter combines discrete PCM and true one-bit DSD circuits to avoid resampling DSD to PCM. The LampizatOr handles DSD up to DSD256, the T+A up to DSD512. Switching between the two meant adjusting the HQPlayer settings. There is still controversy around the DSD formats. Is DSD512 better sounding than DSD256? Why is the Nagra HD DAC which 'only' handles DSD128 the best-sounding DAC at the moment according to many like Edward Hsu? With DSD128, the analog low-pass filter in the DAC must eliminate the >40kHz ultrasonic noise in a non-aggressive way. DSD128 means running at 5.6MHz which creates less EMI/RFI noise than the 22.6MHz of DSD512 to begin with. If the filter leaks just a tad of those super-high frequencies, it might affect the sound negatively, giving the advantage to a simpler more effective DSD128 filter. What about the expected lifespan of output tubes in a tubed DAC? Do they like super-high frequencies? These remain open-ended questions.