What makes speaker's sound big?


Does a speaker need to have many drivers or a large driver area to sound big and fill the room?
I am asking this question because I have a pair of tekton design double impact and would like to replace them with smaller speakers and a pair of subwoofer's to better integrate the bass into my room.
I just borrowed a set of B&W 702S. The are good but the just don't make that floor to ceiling sound that I like.
Maybe I have already answered my own question (: But again I have not heard all the speakers out there.
My room measure 15x19' and the ceiling goes from 7.5 to 12.8'

martin-andersen
Two subwoofers not one. Agree with mid-bass response point.
Yeah, no substitute for how it should be, either speakers or cars or whatever.
The final answer which on these threads is always, sub woofers. 
Sub woofers are like 400 watt amplifiers...why would you want more watts if the first watt sounds like crap. Why would you want to add subs to a system that sounds like crap..
I wouldn't really. In fact, I advocate full range speakers without any subwoofers, but sometimes it is not practical in terms of cost, space, aesthetics.
So yes, big speakers, big high current amps, big turntables, and the right cables. Then it will sound big. Oh, and good recordings and wall current.
Post removed 
One factor no one has mentioned is the quality of the music coming from your source. Better quality source components can make the same music (whether from vinyl or digital) sound fuller and with more presence.

Amplifiers can also make the same speaker sound fuller in sound.