Finally got around to swapping out all of the old HT gear with the new.
Wires all nicely managed, everything plugged in and located in the rack.
Fire it all up and...oh yeah baby!
Everything works and sounds great. I play through some Blu-Rays, listen to some music, throw a couple of games on the xBox at it.
HUGE improvements across the board.
I shut everything down and get ready to head to bed for the night.
As I am walking through the living room, I notice a steady hum at about 60hz coming from the vicinity of my front sub.
I know the sound of that evil bastard, Ground Loop Hum.
It is getting late, so I begin some quick basic troubleshooting. (each step was performed independently. So after each test, everything was returned to original state)
1. Pull interconnect at sub. Hum is gone.
2. Pull interconnect at AVR. Hum is gone.
3. Pull the cable from the dish. Hum persists.
4. Swap sub interconnects around. Doesn't matter. Hum persists in same sub.
5. Connect ground from my surge suppressor to chassis of both amp and AVR. Hum persists.
6. At the sub end, I ground the "shield" connector of the interconnect to the center screw of the outlet it is plugged into. Here is where it starts to get weird. Hum goes away completely with gear turned off but power to gear. Turn gear on, hum is back but even louder.
7. Ground shield of interconnect on AVR side directly to the common ground on the surge suppressor. Hum diminishes slightly but is still there.
8. Plug sub into same outlet the rest of the gear is connected to. Hum persists.
9. Jump the shield side of the sub interconnect to the "negative" terminal of the nearest speaker wall plate. Hum disappears completely. No sound quality issues, speaker sounds fine. Voltage readings on the speaker terminals are normal.
So there you have my weird and wild adventure with my ground loop nemesis.
I am not comfortable grounding the interconnect in this manner.
One thing I did notice is that the hum fluctuated while unplugging and plugging in the interconnect at the wall plate on the AVR side (AVR->Interconnect->Wall Plate->Coax through the wall->Wall Plate->Interconnect->Sub)
Tomorrow, I think I will pull the wall plate and verify that the coax isn't loose on the terminal.
Other than what I have tried, anyone else have any thoughts?