I have a Line 6 M5, only used it a few times since getting it (used). It worked fine the first two times, but last weekend about an hour into my show, I had NO sound coming out of my amp?? I checked all the cables and finally bypassed the M5 (ran a cable around it) and it worked, so I just wrote it off to a bad cable. This past weekend during sound check (different venue), after 2 songs, I had no sound again.... I immediately took the M5 out of the chain and it all worked again?? I was using all new cables to hook it up that last time, so I know it's the M5 and not a cable issue. Everything appears to be working... It all lights up, changes patches, but no sound......Well, a VERY faint sound does come out but you can't hear it unless you put your ear up to the amp. Is this a known issue with these? I'm using a 9v 500ma power supply that came with my TC Elextronics X4, if that makes a difference?