That assumes that you have a perfect circuit. However, the voltage peak to peak may be 7 volts but I would also assume that that is not under load. The base equation for power is voltage x current so the question really is: how much current can the amplifier supply without distorting? You also have to consider that there is a certain amount of resistance applied by the resistors after the opamp in the circuit. If I actually had the schematics I could probably get pretty close to that measured values with equations.
Edited by Sk1n5 - 1/26/13 at 10:34pm