Evening, I now have my components, crossovers, headunit, amp and sub fitted in the car, all parts were working fine in my last vehicle but it sounds terrible in my Cabrio! Lots of alternator hiss and what sounds like clipping when I turn the volume up. I've turned the amp down to half power and the alternator hiss is still there and the crackling sounds when the volume is increased. I've confirmed the RCA leads are good and the earths for the headunit and amp are good , also tried earthing the head unit to the same place as the amp, which didn't work. Guess all there is to try is the amp and h