On Mon, Apr 6, 2015 at 4:54 AM, Fons Adriaensen <fons@linuxaudio.org> wrote:

[ ... stuff ...]

I'd also mention that these days I do most of my computing on a system with a 12VDC power input, and for the last 3 months, that system was powered from a solar-charged 12VDC power system. There is no "ground" in this system, and no noise - the power supply is as clean as you can get, audiophile class in fact :)

And yet ... my "cheap" 12VDC amplifier which is also a USB DAC, suffers from the pin<=>chassis wiring problem. Just touching the USB connector to the chassis of the computer generates noise. It doesn't have to be anything to do with AC power supplies ...