I am rearranging my system and would like to get rid of an annoyance in my setup. I do have a SP1.7 hooked up with balanced cables to my 9B-ST. They are both plugged into the same wall dual power outlet. The active subwoofer is plugged in the SP1.7 via balanced cable but unplugging it does not make a difference.
When I power up the system and the SP1.7 comes I get a rather loud ground loop hum emitting from the 9B-ST chassis. I can play a stream of zeros at 0db and the signal is almost free of ground noise but the ampifier is physically vibrating. When I turn the SP1.7 off it makes no noise whatsoever.
What should I try to get this under control. The hum is very audible from my listening poition and somehow defeats the black background coming from this amp otherwise.
I read that the 9B-SST has upgraded grounding. Is this a known problem that was addressed in the upgrade from ST to SST?
Any help is appreciated.