Network Audio Players/Servers

Comparisons with the Vivaldi APEX [HFN Jun ’22] show small, but measurable, increments in performance linked to the Ring DAC’s new differential operation. For example, the 5.88V maximum output (6V mode) has not changed, nor has the sub-1ohm balanced source impedance, but distortion through bass and midrange has witnessed a reduction in 2nd harmonic from 0.00004 to 0.00003% over the top 10dB of the Varèse’s dynamic range [see Graph 1, below, and note the shifted 0dB to –140dB Y scale]. Such figures are of technical interest only, of course, while the 20kHz figure remains unchanged at 0.0001% as this is a function of the final analogue output buffer and not a digital non-linearity. However, the Varèse’s balanced Ring DAC has delivered a 1dB uplift in A-wtd S/N ratio from 117.1dB to 118.1dB while low-level resolution is now good to ±0.2dB at –120dB. Again, this is all reflective of a state-of-the-art DAC.

The Vivaldi APEX’s elimination of random jitter/phase noise exposed an increase in correlated jitter of 120psec (48kHz/24-bit data), so it’s gratifying to report the Varèse having its cake and eating it – the phase noise remains banished while the Vivaldi’s ±5Hz, ±7Hz, ±9Hz, etc, sidebands are fully suppressed by this differential Ring DAC. A mere ~5psec of jitter remains at ±1.95kHz and ±100Hz (PSU) over all sample rates [see Graph 2].

The frequency response(s), stopband rejection and time domain behaviour all depend on your choice of dCS’s six custom digital filters though, as a rule, the linear phase F2 filter offers the flattest responses, out to ±0.00dB/20kHz, –0.62dB/45kHz and –7.0dB/90kHz with 48kHz, 96kHz and 192kHz media, respectively, at the expense of the poorest (–3.7dB) image rejection. All filters passed the intersample clipping test. PM