I have tried to fix my problem using the various remedies I've found in threads on this and other sites, but to no avail.
My problem began in the usual way. We bought a new Denon AVR, replacing our pre-HDMI Pioneer Receiver. So, instead of the audio and video being split up, now they are combined through HDMI cables. We chose the Denon because it had 2 HDMI outputs and was less than $1000 and could handle FLAC files.
Because the hum was intermittent, I figured it wasn't a ground fault. I have everything plugged into an 8 year old Monster power conditioner (we're a bit out in the sticks and have some power issues). The satellite coax is also plugged into the Monster filter. Our Satellite dish is kitty corner from the "through the wall" point, exposing about 75 feet of coaxial to the elements. I think one of the sources of interference was my neighbor's industrial kitchen fan. There are also airports, submarines, and a Naval degaussing area down the road.
We had decided to upgrade to the Hopper, and we asked the tech to ground the satellite cable. This has actually made the problem worse. We are picking up sump and septic pump activity. My wife is wondering why we upgraded the receiver, especially since she thinks the video is also slightly degraded, having to pass through the AVR instead of running directly from source to plasma/projector.
Last night I was trying to read a CEDIA paper one of your members posted. I believe the point of that paper was that there are doohickeys that can isolate the subwoofer from the hum. I'm not sure I understood the paper well enough to choose a particular doohickey. My back up solution would be to run optical cable from the Hopper, since I don't think the Hopper produces any audio that optical can't handle. I'll leave the PS3 straight HDMI.
Other details. The speakers and subwoofer are AudioSonic, about 8 years old. I did have a Monster directional RCA cable, also 8 years old. I tried a new Rocketfish cable, which did not help. The plug is grounded and correct polarity. My wife has the latest Apple wifi, which is hooked up to cable.
My wife has amassed some points at Best Buy, so we might get the Geek Squad out. But I'm hoping for some ideas so we can point them in a fruitful direction.