Network Audio Players/Servers

The A30's technical performance is best described by examining its host of user-options. For starters there are no fewer than seven digital filters – a mix of linear phase (Sharp and Slow Roll-Off), minimum phase (Short Delay/Sharp Roll-Off and Short Delay/Slow Roll-Off), a hybrid type (Low Dispersion/Short Delay) and two NOS types (Super Slow Roll-Off 1 and 2). All offer a trade-off between pre and post-ringing (or no ringing in the case of the NOS filters) for greater or lesser stopband rejection (69dB, 5.4dB, 69dB, 5.4dB, 1.5dB, 1.5dB and 22dB, respectively) and treble extension (–0.1dB/20kHz, –5.0dB, –0.1dB, –5.0dB, –3.3dB, –3.3dB and –0.65dB/20kHz, all with 48kHz data). The A30's output is phase-inverting with all these filter options.

Also, the upsampling option and 'current mode' have an impact – the former reducing digital jitter from 155psec (48kHz/96kHz) to 130psec, though still slightly 'untidy' [Graph 2, below]. 'Max current' delivers a measurable reduction in high frequency/high level distortion by improving the overload performance of the analogue output stage from 0.0009% ('less current' mode) down to 0.0005% ('max current' mode) at 20kHz/0dBFs [see Graph 1, below]. Distortion through bass and midrange reaches an impressive minimum of 0.00004% at –10dBFs – hence the rescaling of Graph 1 down to –140dB, putting the A30 in the exalted company of Chord's DAVE [HFN Apr '16] and the dCS Vivaldi One [HFN Feb '18]. In addition, the maximum 5.3V output is issued from an amazingly low 200mohm source impedance – making the A30 very 'interconnect agnostic' – while the impressively wide 116.8dB S/N is unchanged regardless of current mode, upsampling or digital filter. PM