I usually go HD500>xlr cable>powered FRFR monitor for my sound and it's very quiet. But at home I decided to go HD500>1/4" instrument cable>front end tube amp for a change. I was greeted with the worst interference I've heard. Sounded like the command bridge of a UFO flagship. I quickly figured out that it was my laptop a few feet away. Turned off the laptop. No more interference. Is there much you can do except move the computer away from the HD? Is this a problem when using 1/4 cable to other power amps?