gain isnt a volume knob...you set gain to the same level as the output of the source unit (whether it be headunit, eq, line driver) volume on eq or h/u is the only way to control volume or how much power is going to the sub. you can reach clipping levels even with gain at 0. depends on source of the music, hu outputs, input power. there are alot of variables. 500 on each should be plenty.