I usually play my electric guitar through Gearbox on my desktop PC. It's helpful for recording as well as keeping the noise down in my apartment. I recently moved to a different apartment and am now having problems with buzzing/humming.
My guitar is connected to the desktop PC via a Line 6 Toneport USB interface. The buzzing occurs as soon as I connect the guitar to the interface with an instrument cable. Sometimes if I tilt the guitar around, I can eventually stop the buzzing by holding it in that specific position. It's pretty hit-or-miss.
I have another guitar and a bass, and both do the same thing as the first guitar. I've tried plugging the desktop PC into several different electrical outlets in the room, as well as different power strips. Nothing seems to alleviate the buzzing. I have a laptop, and I've found that if I connect one of the guitars to that, everything works just fine, no buzzing. I've recorded guitar for a couple years on my desktop at my old apartment with no problems. But now that I've moved here, I can't stop this annoying buzzing.
Any thoughts? Just out of curiosity, I went back to my roommates' apartment and tried plugging my desktop back in. No buzzing.
Well at least you know its not the TP.
It could be ground looping. But the fact that the position of the guitar has an affect could be it is some other local interference.
Do you by chance have a CRT monitor?