You said "6db out of 18db", which means you must be talking about the EQ network built into the amplifier. 6db of boost requires that the amplifier output 4x the power. So if you have the gain set to where the amplifier is outputting 1250w and then apply the additional 6db of boost, the amplifier will try to output 5000w of power at and near the center frequency of the EQ. What's going to happen when that 1250w amplifier tries to output 5kw? Clipping. Negative kicker sx amplifiers have no dials its all digtial through a controller on the dash the amp has built in DSP, Kompressor, and EQ as well as LPF, Band pass, and HPF. The Eq focus is set to flat at 60hz with a Q value of 1.0 which is nothing. As far as gain goes it has three option 1v-2v-4v. It then has an adjustment of gain in db with a high of 18db per channel and a low of 0, 0 is no gain. According to the manual: Gain Menu; Now use the UP and DOWN keys to increase or decrease the gain of the amplifier in .5 dB increments from 0 dB to +12 dB. (.0 to 12.0) EQ Menu; BOOST/CUT is how much you want to boost or cut the equalizer and has a range of -18 dB to + 18 dB in .5 dB steps In which case, if you are using the adjustment that goes up to 18db that would be the equalizer and not the gain as the gain only goes to 12db.