An accurate power draw cannot be obtained without considering the power factor. In essence this means measuring the phase angle of voltage vs current (as well as measuring voltage vs current). The true RMS power figure is obtained by: P = VI cos phi. The cosine of the phase angle is called the power factor. This formula holds for all sinewave sources of power (such as AC from the wall).
How can I measure power draw?
Is there a simple way to measure how much power my components are drawing from the wall? My interest is prompted by experimenting with the PS Audio Power Plant and various conflicting info about how much it draws. (The answer I'd love to get is that there is a Radio Shack box I can stick in between the DUT and the wall, but you tell me...)