simple answer:
750 watts
v * A = W
more info:
VA Versus Watts
An important distinction must be made between power (Watts) and VA. Power is a measure of work, and it is quite possible (common, actually) to have a situation where there is voltage and current, but little or no work. The product of voltage and current is Volts * Amps, or VA, and there is commonly a wide variance between VA and Watts
http://sound.westhost.com/power-supplies.htm#VA-vs-W