Yeah, all the crossovers/equalizers/bass boosts that you might have on your HU should be set flat or to zero. Then you turn your volume 3/4 of the way up... I think you know the rest!
just to clarify...keep turning the gain up as long as it doesn't become distorted...and keep it just below the distortion level. also, my hcca 250 digital reference amp has an EQ button on it, when i push it the bass stops and the subs move up and down with no sound...whats the deal? and what is that button suppose to do.