This is a weird one. My research hasn't turned up much at all.
I have built a gaming/HPTC computer for my home theater. It is in a Silverstone GD06 case, in my AV rack. The rack houses it, the PS3, my receiver and the amplifier for my subs, a professional Yamaha PC4800N.
Thing is, the PC, for some reason, seems to impinge on the sub amp!! It is like a buzz/crackle when the computer is churning (like on startup and such). It's the PC for sure - the noise happens even if the computer is disconnected from the receiver, with the receiver turned off!. (If I shut off the sub amp, no noise.) It just seems to be some kind of physical interference between the PC and the sub amp. I've also tried moving the PC and amp as fair away as physically possible in the rack - noise still, practically the same amount. I have tried another one of my PC's and it doesn't produce that noise, so it seems to be that particular PC.
So - anybody know how to isolate the PC, or shield it somehow?
I'd suggest its electrical noise propogating down cables not over the air (otherwise it would get better when you moved them further apart).
Are they on filtered sockets (i'd expect that they are)? but i'd imagine that they are on the same filtered socket i.e. protecting from noise from the outside world. Can you move one of them to the other side of the filtered socket (probably the PC), or put it on a seperate filtered block.
Sounds like a possible ground fault issue. Most hardware stores or home centers sell a device that simple plugs into any electrical outlet and has a few different colored LEDs that will light up in different configs which will give you an OK or some form of issue code. I dont recall them being very expensive either.
Some audio gear can be very sensitive to even minor electrical issues. By chance is any of this stuff pluged into a power strip. Those can be a real headake to. You may want to look into a power conditioner also. IF the problem is from the house wiring that is.