Leave those gains at zero unless you can max out the hu. Then you can try increasing them. If you can't reach max volume don't adjust them down. Just note what volume you can't play over. Adjusting them down will prevent you from getting full pre out voltage. That is not normal for the equalizer. I've never heard of that before. As far as setting eqs, don't boost weak frequencies, cut the stronger ones. This will help you to avoid clipping your signal. Keep it flat to tune though.