Outboard DACs

Tested in default 'high' output mode, with the volume set to '100', the Discrete delivers a maximum 3.32V from a 142ohm source impedance (balanced XLRs). Although its volume extends to '106', digital clipping occurs at '101' with a full scale 0dBFs input, so '100' is the safe maximum setting. The A-wtd S/N ratio is very generous at 114dB and low-level linearity good to within ±0.2dB over a full 100dB dynamic range regardless of

S/PDIF, USB or network input. In this regard, the Discrete mirrors the performance of many top-end DACs, but in others it very specifically mirrors that of the costlier Premier [HFN Aug '19]. There are subtle differences in engineering between the Discrete and Premier but the biggest lies in the number of R-2R DAC modules employed: four in the Premier, two in the Discrete.

Distortion is low enough at 0.0016-0.014% (0dBFs, 20Hz-20kHz) with a minimum of 0.0015-0.006% occurring at –10dBFs but while these figures are identical between the models, the complement of harmonics is very different – almost purely 3rd harmonic in the Premier but spread across 2nd-7th harmonics in the Discrete. However, the distinctive pattern of distortion vs. digital level [Graph 1] once again reveals the unique behaviour of the Prime DAC's R-2R network with its characteristic 'ripples' between –15dBFs and –50dBFs. Jitter rejection [see Graph 2, below] is also world-class in the Discrete which suppresses any sidebands to <10psec. Once again, this is a function both of MSB's custom clocking and linear phase digital filter [see boxout, p47] which also delivers a full >130dB stopband rejection and sets the ultimate freq. response of the various incoming sample rates. Files at 44.1/48kHz extend to –0.03dB/20kHz, 96kHz files reach –1dB/27kHz and 192kHz inputs roll off at –1dB/30kHz. PM