I understand how to change the gain i just dont understand how to get it where it needs to be?
use a DMM, i think there's a sticky somewhere on it. ( http://www.caraudio.com/forum/showthread.php?t=63933 )
if not, turn your gain all the way down, then turn your headunit up to where your maximum is at your listening preference(i.e if your headunit goes up to 60, but the loudest you ever listen to is 50, turn it to 50) then slowly turn your gain up until you hear distortion. once you hear distortion, back your gain up a little bit and don't go past your usual on your headunit...