First off.. toss out that damn stock deck and get an aftermarket one. The acoustic feedback system is just a microphone built onto one of the rear speakers and basically adjusts the treble upon sensing road noise.

Trust me.. you'll be sitting wet when you hear what an aftermarket deck will do for you, it's expansion possibilities and better cleaner pre-amp signal if you ever decide on an after market amp and speakers.

Take a look at postgrungejunkie's thread about his car and scroll to the bottom for deck suggestions... most everyone will agree that alpine is a deck everyone likes (except me.. they just look to dam ugly to my eyes )