To set the bass, treble, fader and balance controls to their "flat" position, go to "set up" button with the system on and dial every parameter to its center position. That is the starting point for tweaking the system to your own listening preferences. Actually I find the "flat" response curve of the treble and bass to be pretty close to my liking but I have changed the fader and balance settings to place the "sound stage" more to my side of the vehicle. BTW I really like this particular Bose system. After having had several high-end systems in previous vehicles including ones from BMW, Audi, Volkswagen, Mercedes, and Cadillac, this system seems to hold its own against any of them. I think it's very good for a factory system. Hope this helps!
