If the subs are 750w RMS, then you need 750 watts for each, equalling 1500 watts RMS.

If they are DVC, and are 2-ohm voice coils, then when wired together, you are going to have a 2 ohm mono, 1 ohm stereo, 4 ohm stereo, or 8 ohm mono load, according to your parallel/series wiring configuration.

Most amplifiers are not 2 ohm MONO stable. In this case, I would suggest (2) amplifiers that put out 750w RMS at 4-ohm mono. Then put one amplifier per subwoofer. Also, have a professional set the gains using a multimeter or oscilloscope so that the subs live as long as possible. (i.e. just because the gains on the amps are pointed in the same direction does not mean they are putting out equal power).