Filling a 6600 Cu. ft. room


Hi there I am curious to see just how large of speakers and how many sub woofers it would take to fill a 30x40 space

Its a barn and has vaulted ceilings obviously due to a barn.
Im not certain what the spacing up there would be

Im dreaming of one day getting the genesis 300 when im on top of the world. I havent heard them, I just have extreme faith in arnie nudell and havent seen many speakers that really make me wanna upgrade from B&W Matrix 804's. The JM Labs mezzo Utopias interest me as well as the leagcy focus 20/20. I have heard the new Etopia EM with the VTL Seigfrieds and was blown away and its not the greatest reference but i have the focal utopia components and subs from 2000 or so in my car and they do rock just amazing, I even find myself listening to the jazz staion occasionaly because it comes in well and im not a jazz guy. Any way Ive been looking at the Velodyne HGS18, Paradigm Servo 15, I know enough to know i can no longer go with what seems cool and I need to get help from folks that really know whats up.
128x128systembuilder
A space that large would benefit from multiple subs....even if you have to buy 'less' sub but more of 'em.
Example:: Spend 3 large on a single mondo sub. OR half that each on a pair? I think the pair would yield more uniform bass and just as good extension as the biggie...
Horns would work best why over pay for a costly dynamic that will be pushed to fill 6000sqft
The question remains: Do you need to "fill that space" or do you need to have good sound in the portion of it used for serious listening?
Ok so in response to many comments.

My listening tastes are mostly Rock, Reggae/Dancehall, I love older bluesy rock. A little Hip-Hop, Rap, Funk, R&B and I plan on watching movies on it as well.

I want to have a um kind of blend between filling the space and dedicated listening area. More towards msolid listening space where I can still rock out while working around the house or cooking. Part of me would prefer to do a second system where I could do inwall speakers throughout the house for such purposes but the expense to be worthwhile wouldnt make sense to me as I want to build one fine system

As far as Subs go I have been looking into the Velodyne HGS15's and 18's as they have come down signifigantly in price and velodyne can fix the amps for me as there only 2 hours away

The most important thing to me is getting strings of a guitar right and being able to take a little bit of serious pounding. If its a reference I have found Equitech really puts out the sound im looking for. I know its just a conditioner but it really makes the chords just seem right.