I have two dedicated 20 amp cicuits for my HT gear. One for just the amp and another for everything else. Everything was fine until I added the external amp. After adding the amp I had the dreaded ground loop hum. Anyone who has ever had this problem knows that the hum is the most EVIL beast to ever grace a HT. Over the past four days I'd been battling the beast one step at a time. To use my amp until I had time to tackle the beast properly. I used a 3 to 2 prong cheater plug(a temporary solution only). I started to trace the problem where most ground loop hums come from(DSS or CATV). In my case since I don't have CATV it was my DSS. Disconnecting my DSS coax cable proved that it was the culprit. I checked my DSS and it was bonded to a cold water spigot, I disconnected that and I bonded it to the house ground. This reduced the beast by 50%. To get rid of the other 50%. I grounded the DSS receiver to the amps chassis by running a 14 gauge speaker wire from a screw on the chassis of my DSS receiver to the chassis of the amp(remember that the amp is on a different circuit than the DSS receiver). I spoke with the electrician that put in the amps dedicated circuit and he says that instead of grounding the DSS receiver to the amps chassis. I could have grounded the DSS receiver directly to the dedicated recepticle the amp is plugged into by grounding it to the screws that hold the recepticle in it's box. Either way he says what I did, accomplished the same thing since the amp is plugged into a grounded recepticle it's OK to ground to the amp. Now the beast is dead silent unless you put your ear right up against a speaker. From even 6 inches away you can't hear a thing. This I can live with because I'll never be 2-3 inches away from my speakers. Sorry for the long note. I hope this helps someone else rid this beast from their HT. ooooooooooo whoooooooooooooooooo. The beast is dead. Silence is golden.