Sound problems with a Kenwood KDC-MP342U receiver?

I recently got a Kenwood KDC-MP342U receiver installed. It replaced the factory radio in my 2004 Toyota Matrix. To my ears, the sound doesn't seem crisp and clear when listening to AM/FM radio and listening to songs on my iPod Touch (primary reason why I decided to upgrade). To my ears, All I can hear, at the loudest point, is the artists vocals. All songs on my iPod Touch are encoded at the highest bit-rate (256). When I got the receiver installed, I didn't get the speakers changed out. Could that be the problem? Is anyone else having this same problem?