id start with making sure you dont have a bass boost or loudness feature turned on
then id set your eq all in the middle position, no boost, no cutting frequencies
that can help prevent clipping (a kind of distortion)
then, if your deck has crossovers, make sure youre using them. 80 or 100hz, should be good
if youre not using a crossover, than can allow your speakers to move too much, causing distortion. speakers can only move so much before they distort the signal
if all thats good, you need more power.. an amp
then id set your eq all in the middle position, no boost, no cutting frequencies
that can help prevent clipping (a kind of distortion)
then, if your deck has crossovers, make sure youre using them. 80 or 100hz, should be good
if youre not using a crossover, than can allow your speakers to move too much, causing distortion. speakers can only move so much before they distort the signal
if all thats good, you need more power.. an amp