 mach 460 stopped working... diagnosis?
1998 mustang coupe
okay, basically- as most of you may already know- the mach 460 system for a 1998 mustang coupe consists of 3 amps: one in the front that powers high and mid ranged sounds for the front and rear speakers, and two amps in the back (one on either side of the car) that power the front and rear low ranged sounds. I do have and aftermarket amp hooked up in the loop of wires that connect the system, but i don't think that should be the problem because when i first bought the car it was already all hooked up and working fine.
fairly recently, i was driving around with the radio playing pretty low and pretty much all my speakers stopped working except for the front two tweeters/ mid speakers and the back mid speakers (the bass on the rear mach speakers were not working)
because it was a fairly old car and the cd player had already stopped working, i figured that the deck was the problem. So a friend and i replaced the deck and it still was giving the same problem.
at this point, i'm thinking that one of the mach 460 amps that are in the loop of wires has stopped working and is no longer passing a signal along to the others.
what i'm not sure about is how to make sure this is the problem without cutting all kinds of wires and trying to bypass all the amps until i find the one thats not working or to find out that that wasn't the problem in the first place.
ANY suggestions on fixing this problem would be greatly appreciated. thanks in advance for your help | 
