Sub output: Is it the woofer size or the rated RMS


In any subwoofer output, how important is the Watt output versus the woofer size? I have been reading reviews on some subs such as Earthquake, Sunfire and JL audio. The Earthquakes (15" woofers; ~650W) have reportedly more "slam" than the Sunfire (1000W-1500W, 12" woofer), or the 650W-750W SVS, or even the fathoms.
And each of these are box subs.
Or is it really about the proprietary technology unique to every sub?
In other words, what really influences a sub's output for all the wonderful things we want in a great sub?
dogmatix
((doubling or tripling drivers does lower their f3 point))

I meant to say does not.

The biggest factor affecting sub performance is air displacement and that can be a small cone with a large displacement or a large one with a small movement or something in the middle. Either way it’s a compromise just like all speaker design but for accuracy at any size it requires good engineering and there are plenty of good designs on the market and lots of not so great ones. Choose carefully grasshopper