Help - static noise in speakers

I hear static in one speaker.  I switched the speaker wires and the static changed speakers, so I guess its coming from the amp or from the speaker wire.  Its not loud but its noticable.  I have a Mcintosh 352 integrated tube amp and Audioquest Red River cables.  It happensd regardless of the input, so its not the table or the streamer.  

Does anyone have any ideas beyond taking the amp in for service?

Thanks