Tried to clamp my amp, have a question.

[Jessica]

I put my DMM on my 9105d, I Also hooked the dd-1 up while i was at it. I played the -5db 40hz tone which is what i set the amp gain with. The amp has two speaker terminal sets but its a mono block. I don't think this would effect my readings, i hope.It's wired at 2ohms ( two 4ohm subs, 3.8 each on the dmm)

Anyway, at just under clipping i get 51.9v, if i go above that i can get 60.1v. Of course the dd-1 is lit up like a christmas tree when i do that.My question is without a "clamp" and knowing amperage, how can i know what my wattage is? Is this chart fairly accurate?

here is the chart;