With me the issue is the power brick from the laptop. When the laptop is powered by the brick I hear a LOT of spurious electronic radiation. Old school fix used to be wrapping it in foil, but that didn't work. I have gone so far as to plug the laptop brick in on another circuit from another part of the house with a long extension cord and it still caused a hum. So I use it on battery power when doing anything I care about, like dumping to the mixer to feed it to the 8 track recorder. It normally stays plugged into a Furman line conditioner. Even then I get the noise.