Use a pair of subs to get the "punch". Use the a high pass filter to protect your main speaker woofers from over travel (run them full range when you listen at sane levels). Use plenty of clean power so you dont clip and trash the tweeters. I use speakers with 5 1/2" or with 6 1/2" woofers and they both play very loud, but your room is much larger than mine. Some speakers of modest size can play surprisingly loud if given lots of {quality) power.
With a room as big as yours, pro sound may be the way to go, but dont discount the subwoofer option. Most PA type systems dont play below 40hz, even if they have large woofers.
With a room as big as yours, pro sound may be the way to go, but dont discount the subwoofer option. Most PA type systems dont play below 40hz, even if they have large woofers.