I have recently got my hands on kenwood headunit with cd changer and installed it but i get interferance from car engine through the 6 x 9s also sub pops etc.
There are two earths from the amp even tryed to put direct earth from the battery and also by passed the power control with live from battery but nothing.
Funny thing is if i unplug the power control from the head unit it works fine through normal speakers. Cant work out whats pumped is it the head unit the sub the speakers or the amp? I have the spl amp from motorworld