I just got a 2005 S60 2.4. Its got the HU-650 radio. I'm going to be putting in a sub and i was wondering which wires i plug the amp into. I've read about the volvo's having a factory amp in the car, but i couldnt find it, its not under the passenger seat, behind the dash maybe? If its behind the dash would it be easier for me to splice into the rear door speakers? I've got an adapter that turns speaker wires into rcacablesthat i used on myprevious car, butI dont remember if i spliced inbefore or after the amp, does it matter?im thinking that it does but i'm sure.....I've hooked up an amp before but i am by no means an expert. Thanks in advance for any help!

James