There are more factors than that Phand.
Such as what ohm load the sub is. What ohm load the amp puts out is max rms power. Does the company rate its power at 14.4 volts or say 12.5. What kind of box is the subwoofer in. Some companies, like kicker reccomend less power in a ported box. What kind of music do you listen to. These questions should be answered before matching up equipment, but rarely would reccomend that much of a difference. And by the way a GAIN CONTROL IS NOT A VOLUME KNOB! Jriggs this is not a shot at you,its just you see that in this forum alot and it is incorrect. Inexperienced consumers will read this then blow up thier shit and blame the equipment.