If the specification is accurate and you want to max out the volume you will need 750 watts x 2 for stereo into 8 ohms or 1500 watts x 1 into 4 ohms for a mono amp for non stereo use (speakers hooked in parallel).
If you don't need to max out the volume then it will depend on the efficiency of the speaker in the cabinet. This spec is given as Xdb volume with 1 watt input at 1m from the speaker. The higher X is the less power you need to play loud.
Power handling is not a standardized measurement so it's not clear how long the speaker will take the amount of power in the specification. Some makers exaggerate the power handling. Others are conservative since they don't want you blaming them for blowing the speakers.