I'm curious as to why this is relevant. Obviously you are trying to measure this for a reason. Can you explain?
What is the name of the tool?
Forgive my absence of knowledge, but what is the name of the tool that one uses to measure the wattage coming out of ones speakers. I called it a watt meter to my family and got something that measures the watts and current coming from the outlet to the powered device I was using instead, for Christmas.