[Wildman]

Ok, this may sound very silly, but its worth a shot. Try reversing the wires on ONE of the speakers, JUST ONE. See if that makes it better. Buddy of mine had a pioneer deck installed, then we put in some 6x9's and could not figure out why the bass was so crappy. All the wires were correct, but then after days and days of screwing around with everything we could think of, I switched the wires on just one speaker and it blew me away cause one speaker was pushing out while the other speaker was pulling in cause they were wired opposite. The sounds were essentially cancelling each other out. Stupid and simple, but worth a try