Disc Players

Regardless of whether it is driven from the SACD Transport via I²S, or from a server via USB, the PMG Signature 512 DAC's maximum balanced output is 3.95V from a flat 97ohm source impedance while the A-wtd S/N ratio reaches 108.5dB (all re. 20Hz-20kHz). The latter is some 10dB behind what can be achieved [HFN Feb '26] but does nothing to blunt the DAC's excellent ±0.4dB resolution over a full 110dB dynamic range [red trace, Graph 1]. I discuss the 94dB stopband rejection and variable responses of PS Audio's three linear phase digital filters in our boxout [see boxout] otherwise all the tests here were conducted at DSD256 sampling with the F1 filter. Distortion extends to very high-order (beyond 10th) harmonics but is still a low 0.0002-0.0007% at peak 0dBFs level (re. 20Hz-20kHz). It increases smoothly thereafter with decreasing digital level aside from an anomaly between –50dBFs and –80dBFs [black trace, Graph 1] which presumably indicates a non-linearity in the mapping of PS Audio's novel PureStream DAC solution.

Jitter beyond ±20Hz is very low at less than ~10psec via all inputs/sample rates, including DSD over I²S, but as the 100x zoom FFT [grey spectrum, Graph 2] illustrates, there is ~140psec of very low rate/infrasonic jitter centred on a ±4Hz modulation that again, presumably, falls outside of the 512 DAC's PLL. In all likelihood this is of technical interest only. (Incidentally, the 121psec recorded for CD via the SACD Transport only reflects the inherent level of the 16-bit J-test pattern.) Finally, the balanced, 'minimum feedback' Class A output stage offers a fine 125dB midband stereo separation and a sub-5Hz low frequency extension – the latter courtesy of its DC servo'd output stage. PM