Thought I would share this with you for its humor.
I spent a whole lot of time last evening trying to narrow down a ground loop hum in my system.
Everything appeared to be connected together correctly - and all of the power cords go into the same conditioner/suppressor except for the amp separates, but they're all on the same GFI circuits, and since I wired them in, I know the ground is good.
So I started unplugging devices, one by one. Hmmm... no change. Completely disconnected the sub from the power cord and the lead. No change. Did not want to unplug the DVR, but did it anyway. No change! OK, pulled the plug on the whole darned system.
Wait a minute.....
Walk into the kitchen a room away - its the damned refrigerator! Unplug it, still hums!! AAAAHHHHH!!!!
Microwave? Unplug it. Still hums! I'm nearly beside myself with frustration at this point.
Then it dawns on me. I'm on an antibiotic for an ear infection. It is in my head, literally! I walk outside - and hear the hum! I hear it this morning in my office, too....