Ok, I admit I'm not much of an electronics freak (I guess you could already tell that LOL ). So I replaced the MOSFETS and tested the amp. No fuse blew with no audio input (i.e. key in ignition, empeg on, RCAs disconnected). I connected the RCAs and everything worked just beautifully, perfect sound. I bolt everything down, make sure everything is nice and tidy, start the car and the fuse blows again! I open the amp and now the same two MOSFETS but on the other channel are blown. Obviously, there's something fried that's common to both channels. But all compoents that I could visually inspect and measure with a multimeter check out fine.
Why was it running without the engine on but blew once I started the engine? Where could a difference from 12V to 14V make such a huge difference (It's a 30A fuse that keeps blowing)? When I tested the amp with the engine off, key on, I even turned the empeg all the way open and it worked just fine. Where do you think should I look with a description like this?