Network Audio Players/Servers

Bel Canto is making excellent use of ConversDigital's CDMCM-2121 DLNA 'Complete Audiophile Receiver Module' here, mounting this comprehensive network audio solution on top of its own DAC board. While Bel Canto's free Seek app runs on Apple's iOS only, ConversDigital offers its own 'mconnect Control' App, available for both iOS and Android platforms. For the purposes of testing, I employed the Seek app on an iPhone which quickly provided access to test files over both network and via a memory stick in the USB-A port. In both instances, and over all sample rates from 44.1kHz-192kHz, jitter was remarkably low at <10psec, although some uncorrelated (noise-like) jitter is evident from the broadening of the J-test signal [see Graph 2, below]. The partnering PCM5102A DAC is employed here using its integrated line-driver output and while the chip is described by TI as a '112dB Audio Stereo DAC', in this instance the practical A-wtd S/N ratio was a ~17-bit 101.5dB.

Subjectively, and with useful musical detail rarely captured at this level, a little extra white noise is often no bad thing for digital audio. Otherwise, the 2.08V maximum output meets TI's specification but the 470ohm source impedance is still sightly high. Distortion is held to a steady 0.002-0.003% over the top 30dB of the Stream's dynamic range through bass and midrange frequencies [see Graph 1, above], increasing only over the top 10dB of its range at very high frequencies (0.03%/20kHz/0dBFs). The linear phase digital filter offers a 63dB stopband rejection (re. 20kHz at 48kFs) and an extended response reaching out to –0.13dB/20kHz with CD/48kHz files and to –2.8dB/45kHz, and –4.4dB/90kHz, with 96kHz/192kHz media, respectively. PM