[Puma Cat]

Originally Posted by W9TR

I use a battery operated tablet to mitigate the issues highlighted by Stephen. No SMPS noise source. It is connected to my Yggy via a 1.5M Platinum somethingorother from WW.

Dedicated end point devices may produce less noise on the USB lines. But I would have to measure it to be convinced because I’ve seen some terrible digital designs from high end audio companies.

There are a number of noise components that are pervasive from the use of common digital devices used in a digital front-end, e.g. routers, network switches, NAS', fiber media convertors, etc. One noise component is leakage current, which causes ground-plane noise on a DAC’s internal ground-plane.

And, here is a key point: while the isolation transformers used digital devices e.g. Ethernet switches will block DC and low-source (AC) leakage, they DO NOT block high-source-impedance leakage current. This class of leakage current is current is actually an AC current, and therefore is not blocked by ioslation transformers. Its pervasive from the use of SMPS and causes increased clock-phase noise.

This noise component was not even discovered until Oct. 2017 by John Swenson who had to build bespoke test equipment to detect it, so obtaining data for it at this time will be made available when John Swenson publishes this data at the Uptone site (I know these measurements have been a work in progress for some months now), so stay tuned.