hi guys, I'm new here. I have a hartke A100 in my rehearsal studio. the speaker driver kinda blew, distorts like crazy so I can't turn up the volume. Same problem when plugging in cdplayer to the RCA audio inputs. Luckily still under warranty, I have sent it for repairs . I'd like to know what are the usual causes for amps to blow ? Can plugging in line-out from bass multieffects to the amp's passive input be a factor ? or "defective" bass pickups ? or too much distortion from bass pedals ? or simply the amp is lousy ?