Outboard DACs

Some early implementations of the ESS ES9038Pro DAC, including Matrix Audio's X-Sabre Pro [HFN Nov '17], had higher levels of correlated jitter than might have been anticipated, but in the X-Sabre 3 and Element X [HFN Jan '21] the company has evidently improved its 32-bit Sabre DAC-based platform. Distortion is state-of-the-art low at 0.00001-0.00025% across the maximum 4.7V balanced output (20Hz-20kHz), holding to a mere 0.00035-0.00045% over the top 30dB of its dynamic range [Graph 1, below], while the A-wtd S/N is a class-leading 117dB via all digital inputs and resolution true to ±0.1dB over 100dB and ±0.25dB over a 110dB range. I discuss the impact of the seven user-selectable digital filters on time domain versus stopband distortion and frequency response in our boxout, p67, but at its 'flattest' the X-Sabre 3 reaches ±0.0dB/20kHz, -0.5dB/45kHz and -1.0dB/90kHz with 48kHz, 96kHz and 192kHz media, respectively. Otherwise, output is phase positive, channel balance is good to 0.01dB and separation >110dB (20Hz-20kHz).

Aside from the digital filters there's another option for 'jitter rejection', but where jitter is concerned the most important feature is the 'Sync' key on both the remote and front panel. In synchronous mode incoming data is processed natively while in asynchronous mode all LPCM inputs are upsampled to a 48kHz-centric master rate. A side effect of this upsampling involves a reclocking that has a profound impact on jitter - where a synchronous/native 48kHz/24-bit feed suffers a rather 'untidy' 145psec of jitter, noise and other spuriae, the same input processed asynchronously has any jitter and noise squeezed down to just 6psec [see red vs. black spectra, Graph 2]. PM