Ok, so I have a bad hum with my ep500.

Hum is only present when I connect the sub to my Denon 3808 (removing sub cable but keeping sub power stops it). Funny thing is , I have always had this problem at this house, but when I connected the hdmi out from my Denon 3808 to my panny plasma (tv has a 3 prong plug), sub would be dead silent and work as intended. As soon as I unplugged the hdmi it would come back.

Well I just bought a new tv (TCL75R615)... it only has a 2 prong plug and now nothing stops the hum.

I disconnected everything from the avr (all speaker cables and video cables), disconnected the cable line coming to my modem (which was hard wired to router and then receiver via Ethernet), disconnected the OTA antenna line that came into my system, everything. The hum is still present when I only have the sub connected directly to the avr with no other connections. I even tried plugging the sub into the same outlet as the Denon and tried alternate outlets throughout the living room. Even tried a cheater plug on the ep500 and no success. I tested the electrical outlets with a receptical tester and everything appears to be wired properly.

I am going crazy trying to resolve this... any ideas?.

Are you using a trigger cable? Do you have another cable you could try running between your AVR and sub?

Did you unplug the TV from AC? It's quite possible the switching power supply in the TV is conducting noise onto your mains. It's also possible the TV is radiating noise which is being picked up by the sub cable.

How is the hum affected when you set the cutoff to 60Hz and 40Hz through each of the receiver and the sub?

Yay I solved the problem. After 3 hours of trouble shooting and moving things around and using new cables, etc... it took two seconds to fix. The ground screw on the back of the of ep500 v2 was loosened a bit. Tightening the screw resolved the hum completely. Thank God.. I was going insane!

Funny as I think I recall loosening the screw to stop the hum 8 years ago when it showed up when i hooked up my panny plasma...

Good for you. I forgot about that mysterious screw.

thats what she said

Randy, I see you and Blair were out on the lash.