On a completely unrelated topic, could someone tell me what the crossover knob on my amp is and what it should be set too?

is it your sub amp ?
is it a spl set up ?
sq i try not to go over 0-80 maybe 0-100 over a 100 you will hear where the sub is

Im trying to get quality..what does the knob do? Whats a decent setting to put it too?

80
best to try it higher or lower and hear the difference, then you'll know what it does