I have a DirectStream Junior, which is manifesting an unusual ground loop problem, for which I am unsure how to correct.
If I connect a single output (unbalanced) from the DSjr to either input of a 2-channel power amp, there is no ground hum. When I connect the second channel - I get a pronounced hum. To clarify, I can connect left output to right input, left to left, right to left, right to right - it doesn’t matter - no hum. It’s when I add the second connection, I get the hum.
Note that when using balanced connections, there is no hum.
I am experiencing this issue with three different 2-channel power amps (Bryston, Halo, Sony ES). Strangely, I’ve also tried using a pair of monoblocks (Cary 300B tube amps) - and they don’t produce the hum.
Note that for the sake of completeness, I connected the power amps and the DSjr into the same power outlet. The hum persists.
I suppose I should try engaging the DSjr attenuator, to see if that corrects the hum - as there is also white noise present - enough to be bothersome.
Any suggestions as to what might be happening here, and how to address this problem?