I'm also curious if it affects all USB ports on the computer, or only some. (Some PC's have "always on" outlets that supply power even when the PC is turned off

I'm also curious if it affects all USB ports on the computer, or only some. (Some PC's have "always on" outlets that supply power even when the PC is turned off, and I imagine that those take a slightly different route through the power supply.) Anyway, my guess is that there's some line noise that isn't enough to mess up the PC, and the PC is passing it along to some component in the speaker that doesn't like it.