Hey guy, I've been bending my Casio SA-2 and getting to grips with a few of the bends on here, added the volume, drum pads out, I added a power crash out. Since then, something has happened, my keyboard only plays at a really low volume through the speaker and aux out even when i disconnected the power crash mod and made sure nothing is short circuiting... reckon I've blown the op amp, it is possible that I hooked it up to  9v adapter by accident (even worse, I may have even reversed the polarity)? how would i find out if I've blown it? any suggestions, could I have blown something simple to replace?