So many people don't seem to understand, the number and size of subs makes absolutely no difference in how much power an amp draws. The only thing that matters is the impedance you wire the amp to, and the gain. If you take the same 1000 watt amp and wire up a single 10" sub at 1 ohm, and then later change the system and wire up 2 15's to 2 ohms on the same amp, the amp will be drawing less power.
Not meaning to be a dick, just a pet peeve of mine. Running more subs or bigger subs makes no difference on the draw of the amplifier unless the impedance is changing.