Network Audio Players/Servers

Despite worldwide semiconductor shortages Lindemann is one of the very few brands to have secured quantities of Asahi Kasei's superior 'Velvet Sound' DAC – the AK4493 – driven here via an AK4137 asynchronous upsampler. The Musicbook Source II defaults to a Sharp/Linear phase roll-off filter, offering a full 120dB suppression of stopband images and response that reaches out to –0.6dB/20kHz, –0.9dB/45kHz and –6.7dB/90kHz with 48kHz, 96kHz and 192kHz music files, respectively. However, switching the 'DAC Mode' option from LPCM to DSD via Lindemann's App results in erroneous downsampling via the D1 (optical) and D2 (coax) inputs where responses are truncated to 11kHz, 23kHz and 22kHz (all –3dB) with the same 48kHz, 96kHz and 192kHz files, respectively. This same 'issue' was originally reported in our review of the Source 'mkI' [HFN Jun '20] and remains on the 'to do' list...

Otherwise, maximum output, with the volume set to 'Max' (or '80'), is a full 3.95V (balanced) with a 106dB A-wtd S/N ratio. Via the new fixed output this is 2.2V/102dB, respectively, from a usefully low 48ohm source impedance while distortion is as low as 0.0003-0.0007% from 20Hz-20kHz over the top 30dB of its dynamic range [see Graph 1, below]. This is lower, especially at high frequencies, than achieved by the Musicbook Source just as jitter is almost entirely suppressed in the Musicbook Source II – less than 10psec with any sample rate from 44.1kHz-192kHz.

The analogue line in/out preamp offers a gain of +4.0dB, a maximum output of 6.4V (balanced) and an A-wtd S/N ratio of 95.0dB (re. 0dBV). It is a very 'clean' design with vanishingly low 0.00009-0.00035% distortion (20Hz-20kHz re. 0dBV) and a response with very respectable –1dB limits of 5Hz-75kHz. PM