lockingnut

Yes, the guitar did not have to be plugged in. I found it, the wall plug has a bad ground connection. I switched everything over to another and it's much better. Just by jiggling the plug in the wall, the buzz came & went. This weekend I'm replacing an outlet. It's 40 year old house and I expect to see stuff like this. Dunno why I didn't check before going through all this. Thanks guys, Don

Thanks. . . After rereading my own post, it can't be a Win7 setting. The PC doesn't need to be "on" for this to happen. I'll try a new power strip, another circuit in the house, etc.. But, . . . my old HD400 did not do this.

Just as the title says. I use a newer Windows 7 PC, I usb connect to the HD500x. I run a patch cord from the outut jack to an amp (any amp) and there's a 60hz hum, not super loud but absolutely noticeable. I know it's a grounding problem somewhere. I've tried running the amp 0off the same power outlet as the PC, no help. The HD500 doesn't need to be "on", still there. The PC doesn't need to be "on". Soon as I disconnect the usb connect, quiet as you'd hope. I've tried other PC's, same thing. I've tried a laptop, it works fine. No hum. Again, I know it's a grounding issue. The mind boggling thing is, I had a HD400 before I got the 500x. It did not have this problem. Something's different. Anyone got any ideas? Don