F*'ed up Problem

For prom this year I am using my g'mas limo. It's a 93 Lincoln Town car and I wanted to throw my subs in the back, it has an aftermarket cd player in back and has RCA outputs. Also there is a battery that's in the back off the car, I dont think that anything is run off it but it is hooked up to the alternator and is charged. I hooked amp up to this and I can't get them to wang for shit. In my truck those fuckers pounded but the Amp will go into protection mode, everything is hooked up just the same as in my truck, except it's different car and HU. I have the ground wire hooked up to the negative side of the battery in the back and the wires are short. I can't figure it out, I'll be in the back and turn the cd player up and it will dim as the subs hit then everything just cuts out, all other lights are normal and I don't know what the hell the problem is. I've tried it with the car running and it does the same so it's not a voltage problem. Is this a bad ground or something?? Or is it maybe the cd player that's in it, it's some old Kenwood so it's not the greatest but I'd sure like to figure this out so I can go bump, ha. Any help is appreciated so thanks in advance guys!

Also so you know, it's a Boss K580, low name amp but it's worked great for me, and two Rockford 10" Punch Z's. It's just gotta be something with the wiring right?

If you havent blown them already, one of your output lines is probably grounded out or sending a clip signal which is making the amp draw too much power and trip into protection. if it works on another deck I would retrace the signal wires for continuity.