I'm in the process of designing a couple of custom 'cabs' (with the ' marks because its not a single cab per se, but moreso a small speaker array designed for full range sound), and I need to know how many Eminence PSD2002S-8 (as seen here) I would need to keep up with an array of one 18" speaker, one 10" speaker, and one 6.5" speaker. Complicated, I know, but I figure its similar to how full-scale PA systems are set up. I'll eventually tweak it all power-wise so that none of the speakers are overly-loud, but I still need to know how many 80 watt (RMS) horns I'll need to produce volume equal to the other 3 combined. Oh, and if it matters, each speaker size (be it a single 18 or two 10s) gets a maximum of 300 watts tube power to deal with. Or is there some little thing, possible SPL ratings, that I'm just not understanding. If so, I'd like to know to know the real deal! Thanks all!