AURALiC SIRIUS G2 Universal Upsampling Processor

USB interfaces, clocks, and soundcards

This relative simplicity of connection between the devices (once explained) not only makes sense but works out cheaper than many of its rivals. A full dCS Vivaldi stack – for example – requires five AES/EBU and five BNC connectors; twice as many connectors and twice as many types of connector. While you can still spend big on cables in the AURALiC stack, the company has taken a shine to AudioQuest’s Diamond HDMI.  Depending on whether you use them for the digital audio pathway only or both digital and clock pathways, that’s anywhere between £2,000-£5,000 on inter-AURALiC cabling, which compares favourably with the £35,000+ worth of Transparent XL cables used in many dCS Vivaldi demonstrations. Granted, the four-box dCS includes a CD/SACD transport, and the comparisons begin to run out of puff when comparing hardware as well as connections, but it is worth noting that the commonly-used connections for the dCS Vivaldi (commonly top-end Nordost and Transparent) routinely cost more than the AURALiC stack and all its own cables!

The SIRIUS G2 itself is substantially built and relies on AURALiC’s digital smarts as well as its best modules to make it a step up on run-of-the-mill devices. 

 Some of the more outlandish products in this sector act like beachheads; they force you to change direction. You start out with one brand of DAC, but pretty soon the sheer weight of electronics means the DAC you started with gets the boot. The AURALiC concept – although more than good enough to make such changes extremely valid – is different; instead of forcing you to view everything digital through an AURALiC-shaped filter, the SIRIUS G2 simply brings out the best in your existing products. Granted, its abilities gently coax you into exploring more in the AURALiC line, but the idea here is that you already made an informed decision buying that good DAC and streamer and you don’t need to remake that decision in the light of an upsampler, no matter how good. In fairness, I suspect those who have already gone far down one of the many alternate rabbit holes (CH Precision, Chord Electronics, dCS, Esoteric, Wadax, etc) will have a matching upsampling and clock solution, or have one in their sights, but it’s good to keep the options open.

A new and key term in the AURALiC SIRIUS G2 is ‘Universal’. The AURALiC-based pathway that uses HDMI cables to run Lightning communications between the devices is fine, but it’s an AURALiC-only gig; you don’t get the upsampling benefits if you use another brand’s devices. If you aren’t using AURALiC components, the SIRIUS G2 is still entirely relevant. It includes inputs and outputs for S/PDIF coaxial and optical, AES/EBU 110v balanced XLR connectors, and one USB in and two out. There is also a single RJ45 network connector. How this works is as a go-between, connecting between your source and your digital converter, neither of which need to be made by AURALiC. This doesn’t just have an advantage to network streaming; so-called ‘legacy’ devices get buffed up by the SIRIUS G2 too. Connect it between a CD player and a DAC, and suddenly your humble 16/44 LPCM files get given upsampling power-ups like a boss.

More importantly, how you configure the SIRIUS G2 should depend on what kind of DAC you are using. For example, R2R (a.k.a. ladder) DACs respond best to signals that have the highest possible PCM sampling rate, and the SIRIUS G2 will convert the incoming signal to 32bit, 352.8kHz, by-passing the internal interpolation and filtering, regardless of whether the incoming signal is a PCM or DSD-flavoured datastream. On the other hand, the SIRIUS G2 can upsample PCM data to DSD for a Sigma-Delta DAC, but depending on the chip, this need not be the highest sampling frequency. In both cases, the SIRIUS G2 delivers an upsampled datastream with crazily low distortion and noise floor levels. This is one of the secrets of why the SIRIUS G2 is so useful in a system; feeding a Sigma-Delta DAC the appropriate higher bit rate DSD signal allows the chip to operate at a higher frequency, reducing modulation noise, but this only works if the upstream signal is of sufficiently low noise. With THD+N figures when upsampling PCM to DSD as low as -158dB, the SIRIUS G2 feed, it means distortion figures at or lower than those generated by the DAC’s own chipset.

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