So I wired up my brothers bmw, put in a pioneer HU and ran power to a 1200 watt amp with 2 12” subs. Now the 1st amp worked for a few months then just turned off, the 2nd and 3rd worked for a week. I checked and double checked all wires and there’re good. He took it to a radio shop and they said it was because his power and ground wires weren’t pure copper, he left with the system working and the next day the amp went into protection mode. Also the amps were blowing fuses, can anyone give me some advice on what the issue may be. Thanks in advance 

OFC over CCA is not going to cause that.  There has to be a bad connection or crap signal or gain setting issue.