Disc Players

The Soulnote S-3's support for S/PDIF, USB, CD and SACD, plus FIR and NOS filter options, accounted for over 400 measurements here... And the results are illuminating because the filterless (NOS) pathway is not consistent between CD and external LPCM sources, the former affording a far superior performance [see Graph 1]. In practice, Soulnote's FIR filter is the 'Sharp Minimum' option from the ESS9038PRO DAC (not the linear phase example seen on its website), this offering a full 93dB stopband rejection and no pre-ringing on transients - but strong post-ringing - and a response flat to within ±0.05dB with CD. The NOS option has no time domain distortion (no ringing) but also no suppression of digital aliasing and a response that rolls away to -0.8dB/10kHz and -3.2dB/20kHz with CD. There is no appreciable difference in A-wtd S/N (113.5dB) or mainline distortion (0.004%/FIR and 0.0039%/NOS at 1kHz/0dBFs) except at 20kHz where there is obvious overload in the top 5dB of the NOS path's dynamic range [red infill, Graph 1]. CD jitter is 875psec (FIR) and 850psec (NOS), and 510psec with SACD, but this all remains fairly benign as it's caused by ±100Hz PSU rectifier noise [see Graph 2].

LPCM inputs (24-bit) have the same 113.5dB A-wtd S/N ratio and similar 0.003-0.01% THD (20Hz-20kHz, re. 0dBFs) with the FIR filter as with CD but the NOS pathway introduces a higher, 'flat' THD of ~0.007% over the top 50dB of its range [solid pink trace, Graph 1]. Moreover there is significant PSU-modulation via the USB and S/PDIF NOS pathway that is absent via CD. Finally, SACD extends to +0.2dB/50kHz, -6dB/80kHz and -24dB/100kHz with levels of bass/mid distortion, and low-level resolution, that are consistent with CD (there is no 'SACD/NOS' pathway). PM

Above: Distortion vs. signal level over a 120dB range - CD (1kHz FIR, black; 20kHz FIR, blue; NOS, red); LPCM 48kHz/24-bit (1kHz FIR, pink dashed; NOS, pink)

Above: High Res. Jitter Spectrum Comparing Sacd (Red) With 48Khz/24-Bit Lpcm/Usb (Black, W. Mkrs)