If it's just from one speaker it's almost 100% down to the wiring.
Easiest thing to do would be swap the speaker outputs from the amp and see if that affects it. If the hiss moves to the other speaker, then it's an amp problem, but I'd think that's unlikely.
I'd then take the door card off and check all the wiring to and from the problem speaker, make sure all your connections are as good as you thought.
Just how many Yorkshire sheep can you fit inside one exhaust?
Last edited by parapaul; 11-11-2012 at 04:36 PM.