Measurements suggesting too much power

I was trying to see what kind of power i was putting to my 12w6, so i played a 40hz 0db tone, and my multi-meter read about 44v AC. So i plug that into the E^2/R formula, and since my sub is at a 2ohm load, i come up with a rediculous number of 970. My Amp is rated at about 480-500. The only thing i can think of is that its a peak measurement I'm getting. When i multiply the 44v by .707 (to go from a peak to rms value) and do the equation i get about 480 watts, and that works perfectly. But the thing is, every single guide I've read using that method says nothing about getting a peak value rather than rms. So might my multimeter just be broken? Or does it just read the peak value rather than rms? Or am I doing something terribly wrong?