Ok, I dont expect anyone to know why it does, but maybe point me in the direction to look at. I just got the Sony CDX-F7700 Head Unit and a pair of Sony XS-41340H 3 ways speakers. My vehicle is a 1990 bmw 325i. I have a pair of factory speakers in the front, and i replaced the rears with the above mentioned Sony pair. I installed everything myself because I got a discount on the items and would need to pay extra to get them installed (making my discount meaningless). When i turn my system up a little bit, the bass from the back doesn't sound good at all and the music sounds real distorted. I wondered why that was and used the fader feature on my deck to listen to only the fronts and only the backs. My fronts sounded better than my backs did. Could this be due to a bad connection somewhere? I have heard people say sonys are bad, but they shouldn't be worse than my factory speakers. Maybe I need to set a custom EQ on the deck? The highs and mids seem to be ok, but the bass is just crap. Maybe there should be a cutoff point on the bass its pumping out and get a sub (which i plan to do soon) to take care of all the bass. Any suggestions would be much appreciated. Also I was going to try moving the sonys to the front and placing my factory rears back in and seeing if that sounds any better.