Outboard DACs

As we’ll see, the core technical performance of Topping’s D900 – S/N, distortion and low-level resolution – nudges at the state-of-the-art alongside Chord’s DAVE [HFN Apr ’16], the Mola-Mola Tambaqui [HFN Nov ’19] and dCS Varèse [HFN Feb ’25]. However, at the price, the D900 has no technical peers. In ‘5V/Line Out’ mode, its balanced/phase positive XLR output delivers a maximum 5.1V from a 100ohm source impedance with a 117.4dB A-wtd S/N ratio (DAVE, 117.3dB; Varèse, 118.1dB; Tambaqui, 118.5dB). Low-level resolution is good to ±0.1dB over a full 110dB dynamic range with an error of just –0.5dB at –120dBFs [red trace, Graph 1] while distortion is just measurable from its residual 2nd-4th harmonics at higher frequencies. At peak (0dBFs) output this amounts to 0.00004-0.0003% (re. 20Hz-20kHz), comparing very favourably with 0.00002-0.00008% (DAVE), 0.00005-0.0005% (Tambaqui) and 0.00003-0.0003% (Varèse). Naturally, this is of academic interest only, with zero direct impact on sound quality, although the ‘knees’ in distortion that occur at ~–65dB/1kHz and ~–40dB/20kHz [see Graph 1] do illustrate a specific wrinkle in the PSRM DAC architecture [see boxout].

Jitter is well below 10psec with all sample rates, and phase noise almost entirely suppressed [see Graph 2], but it’s the (fast) linear phase digital filter that sets the very fine 94dB stopband rejection (26kHz re. 22kHz at 48kFs) and response(s) that extend to –0.26dB/20kHz, –1.2dB/45kHz and –4.5dB/90kHz with 48kHz, 96kHz and 192kHz media, respectively. The low frequency response is flat to below 5Hz while channel separation is >130dB midband and channel balance good to 0.02dB – another set of figures unlikely to be matched by any partnering amplifier! PM