On 6/5/2015 1:33 PM, Michael Hennebry wrote: > It's a desktop in an old house. > The outlets have ground-fault protection, > but the third prong is ungrounded. > not sure how GFI would function at all without a valid ground, unless the GFI is wired to neutral, which is dangerous on its own. you might get a 3-prong-to-2-prong adapter and plug the PC into that, leaving the ground wire floating, and see if that works. As most desktops have the AC ground pin wired to the chassis, floating the chassis might well eliminate the hum. also, things like fluorescent lamps can greatly contribute to hum, although that often sounds like a buzz. lamp dimmers too, try switching any dimmers in the general area to either 100% on or totally off. > It's an Insignia NS-PAH5101 > It does not have a separate power source, > just plugs for the pink and green sockets. > The cables are pretty thin. > If the problem is shielding, > is there something I could do to shield the cables? not really, the wire itself has to be shielded coaxial wire. if its actually the headset itself, I'd suggest getting another one. I've had better luck with USB headsets of late instead of analog ones plugged into on-board audio, as the onboard audio microphone inputs are generally of very poor quality. -- john r pierce, recycling bits in santa cruz