Equalizers are used to reduce areas that are adding coloration, not to boost to correct for inadequacy's of the system or speakers. They are generally used to help create a flat and uncolored frequency responce because of interactions of speakers and room acoustics.
Boosting like Maniac had mentioned can put the system at risk because your now putting excess strain on the speakers and amplifier.
There is no one setting for every system, each system must be adjusted to compensate for coloration's in the responce.
So in other words learn how to use a equalizer otherwise your much better off not using one at all.
