The other day I accidently plugged my patch cord into my bass while the amp was on, and the volume dropped by at least half. Could that be... 1) a blown fuse??? (amp or speaker) 2) a blown preamp tube?? 3) something else?? I haven't had time to go back to the jam room to check if it's o.k. now(I hope), just wondering if this has ever happened to someone else??