What the hell, I was trying to lay down some tracks for my new guitar player to learn and when I plugged my bass in I get horrid hissing under every note. Its steady, but only when the bass is generating sound, if I mute the strings or turn the volume off there's nothing. Its not RF because it doesn't change as I move (which RF usually does, right?). It doesn't seem to be grounding because no matter where I touch on the bass there is no change in sound. I took the backplate off and looked for frayed wires or visible shorts but saw nothing. What the hell else could it be and why did it start litterally overnight?