How many watt amp is needed for 2 polk audio 12" subs maxing out at 720 watts?

Is that the peak rating of the subs? If that is the peak rating I'm going to assume both those twelves together are running at 300-500rms. So in theory you only need one amp, a mono block to be exact running at either 500wrms @ 2 ohms or 4ohms whatever impedance your subs run at.