[keithdixon]

Amps within the door don't seem to go bad too often.

Double check the wiring, if not swap out th amp in the door to check

Swap left to right to see if the problem goes with the amp

 

[keithdixon]

Your right the signal - sound comes to each door amp through 2 wires and is split in the amp to the speaker.

No sound from some of the speakers is either duff speaker, duff wiring (amp to speaker) or duff amp

try swapping the amps