Assuming you used the peak hold feature on a DMM and clamp - you calculated VA (apparent power), not wattage (actual power).
To get wattage - you would need to know the efficiency (power factor) of the amp at the impedance you were playing, so subtract 15-20%.
Originally Posted by blockburner
4465 at 14.4 clamped
Oct. 24-25th, 2015 - Sedalia Missouri