When setting the gains with a DMM I always use the settings I will be listening with (or the most that the sub will see). I.E. Generally the sub is at +2 when bumping and my equalizers are already set to what I like. This way you know how much your sub is getting in comparison to setting it with everything flat and off and then turning it up after the gain. Granted, this probably won't make a change with your situation..just a little advice. Also Subsonic should be dropped a bit if you're looking for lows. With that amount of power and enclosure size you shouldn't have to worry about bottoming those subs out anytime soon. I keep mine at around 15 or so and never have any problems with bottoming out...but as usual every situation is different.