Pre/Power Amplifiers

Although Lindemann has adopted the latest 'Velvet Sound' DAC from Asahi Kasei – the AK4493 – it has side-stepped the optional six digital filters in favour of native sample-rate processing. The response and alias rejection of the Musicbook Source's default mode are comparable to a 'Sharp' roll-off filter, offering a full 120dB suppression of stopband images and response that reaches out to –0.3dB/20kHz, –1.8dB/45kHz and –8.7dB/90kHz with 48kHz/ 96kHz/192kHz music files, respectively, via the network input [192kHz file, green trace, inset Graph]. The S/PDIF inputs behaved oddly on test, with a –6dB/8kHz response using 48kHz files and 56kHz limit with 192kHz files [red trace].

The AK4493 DAC accepts up to 768kHz PCM and 22.4MHz DSD but is 'driven' here via an AK4137 asynchronous upsampler that also includes an LPCM-to-DSD data converter. This is the chip behind the DSD setting in the 'DAC Mode' menu option in Lindemann's App. However, all LPCM inputs look to be downsampled to 44.1kHz before conversion to DSD, resulting in a 20kHz response limit and steep cut-off [black trace]. Furthermore, while jitter remains spectacularly low in DSD mode, noise is higher resulting in a mere 95dB A-wtd S/N ratio. So, yes, I would expect a subjective difference between the 'PCM' and 'DSD' modes here. PM