Network Audio Players/Servers

Melco's flagship N10 is not only a music storage device but, like the Pro-Ject Stream Box S2 Ultra [HFN Oct '18], Roon Nucleus+ [HFN May '18], Melco N1ZS20/2 [HFN Jun '17], N1ZS10 [HFN Feb '15], N1AH40 [HFN Aug '15] and N1ZH60 [HFN Jun '16], it is also a transcoding/signal conditioning device. Consequently, any uplift in performance over a conventional NAS or PC/Mac 'delivery service' can only be inferred via a third-party player or DAC. The jitter suppression and/or galvanic isolation of the attached USB DAC is a factor here, so a DAC with excellent data recovery/re-clocking may not express a significant difference. Similarly, a DAC that incurs jitter at the chip level will suffer the same jitter sidebands in the analogue domain regardless of the coherence of the digital data.

For my tests Melco's latest (v1.02) firmware was installed and a series of alternative outboard DACs driven via the N10's 'USB DAC' output. The AC-powered Oppo Sonica DAC [HFN Oct '17] still showed a low-rate skirt of uncorrelated jitter – the cause inside the Sonica itself. A typical PC-to-Sonica USB connection yielded 155psec of jitter, falling to 114psec via the Melco N1ZS20/Sonica [black spectrum, Graph 1] and traded here for a more complex pattern at a near-identical 115psec [red].

Hub-powered USB DACs often provide a good indication of incoming data integrity and noise on the +5V supply, and here iFi Audio's iDSD DAC showed a drop in jitter from 140psec to 15psec. Chord's battery-powered Mojo [HFN Jan '16] witnessed a huge improvement from its typical PC/USB jitter of 50psec and S/N ratio of 103.8dB to 12psec and 113.7dB, respectively, via the N10. In this case, the right channel demonstrated the most significant jitter suppression, just ridding itself of the minuscule residuals seen with the N1ZS20/2 [black versus cyan spectra, Graph 2 below]. Every little counts! PM