On 02/13/2017 03:01 PM, mick wrote:
Hi Brian,
You don't mention which unit you have, but I'm using a Behringer UCA202
feeding a home-brew headphone amp. There's no apparent background noise
at all. I'm using a quite good quality lead between the Behringer and the
amp to prevent noise being introduced here. I've not got any sort of
fancy power supply or earthing arrangement.


I wonder if the OPs issue is an earth loop issue, perhaps combined with
switch mode PSU noise? I've had horrendous noise when feeding a laptop
or netbook to an amp. Run off battery and the problem goes away.
Adding audio isolation transformers also makes the problem go away.

I could have posted this anywhere in this thread, but here is a good
place. In your example of the headphone amp is it run from batteries or
from a floating, ie not earth referenced, PSU?

Pete