I was at the Bass Club yesterday trying out 12's when the cabs started to let out a slight hiss. It wasn't the tweeters, because I had all of them turned off, and it wasn't my bass because even with my bass unplugged it hissed. Mark said that those cabs had never hissed before, so I figured that it was my head. I went home and tried it on my cab, and there it was again, a slight hiss. I'm convinced that it's my B2R. What could've happened? How can I fix this?