Ok, I'm not saying this thing is a killer amp, but it works fine to practice guitar on. And personally I've only built the little gem which uses a single 386, but I know several others that have built the bridged model. Maybe when you are only playing guitar on it, it doesn't matter? But from what I understand, its harder on a chip using it for guitar than for regular am/fm etc. I've run mine on 12volts at 8ohms for hours with little/no heat out of the 386, NO heatsink at all.