Network Audio Players/Servers

Parent brand Novatron makes great play of the fact its X45 'Pro' version is equipped with a pair of ES9038 DACs, and while this latest iteration of the ESS 'Sabre Reference' family has not always proved as straightforward to implement as the ES9028 and ES9018, its performance here is exemplary. Maximum output is 6.2V (balanced XLRs) from a low 48ohm source impedance (increasing to 150ohm at 20Hz), assisting a wide 118dB A-wtd S/N ratio and low distortion that's typically ~0.0002–0.0006% over the top 30dB of its dynamic range through bass and midrange [black infill, Graph 1 below]. There is some variation in performance with sample rate, however, for with 44.1kHz/48kHz digital inputs the output is clipped at 20kHz [blue infill, Graph 1] but not so with the same 20kHz/0dBFs input at 96kHz, 192kHz, etc, where distortion is just 0.003%.

The digital filter also looks to change with sample rate – the minimum phase type invoked with CD/48kHz data yielding a response that's flat to 18kHz within ±0.02dB (–0.34dB/20kHz) but with a stopband rejection of just 21dB. By contrast the response rolls away more rapidly with 96kHz data to reach –8.75dB/45kHz. Then, with 192kHz music files, the response flattens out again, actually 'peaking' by +0.25dB/80kHz and falling to just –0.15dB/90kHz. As promised, jitter is fabulously low whether the X45Pro is fed via its digital inputs or from media ripped and/or stored on the captive HDD. The figures for 24-bit data are just 12psec, 6psec and 10psec with 48kHz, 96kHz and 192kHz data, respectively, while ripped CD is also state-of-the-art at 118psec – the figure limited by the 16-bit data pattern of the jitter test [see Graph 2, above]. PM