I can't give you optimum settings, only because it is subjective, some people like a lot of bass, some people like the hear every note and might heighten the treble....I would say experiment with the music and the source and set it to your specific tastes, I would include sitting in the back seat as well if you'd like to have the passengers enjoy the sound. I personally would make only one suggestion; that would be to have the fade setting on tick to the rear, it seems to be better balanced....again, only my suggestion.. now if we have any audiophiles here I'd love to know the settings they suggest..