Seriously man, you have no clue as to what the gain knob actually does. It is NOT a direct 1 to 1 relationship with out how much power you get out of the amp, max gain does NOT mean max power, it's possible to get max power out of your amp with the gain at 1% if you have high enough input voltage. The gain is there to match the input voltage, which in this case is your HU's pre-out voltage. Not every HU is the same so they have to allow the end user to adjust it. Having a 2V input requires more amplification then an 8V input, but if you have your gain set higher then it needs to be, it's going to clip the hell out of the signal, resulting in a lot of extra heat, and in the long term it will destroy something. Now regardless of how hard you think your driving your subs, set your **** gains the right way.