If your radio has the ability to set individual frequencies for each speaker - use this and redirect low frequencies to the speakers larger, the best way to do this, adapted (usually located in the rear). If you have a subwoofer, then it usually is a separate section of the settings.
Using the tools of the Fade and Balance set of sound you're most comfortable with. Music, as a rule, has a stereo, so four (or more) speakers to play it is not required. However, if your speakers reproduce different frequencies, it makes sense to experiment with a selection of some of them out of the picture.
Adjust the loudness so that low frequencies are not lost at low playback volume, but not buzzed at high.
If necessary, adjust the frequency pattern of your sound. These settings are very individual and depend on the perception of the listener, the speaker type and genre you are listening to music.
Listening to music, podpravlyaya settings until, until you are satisfied.