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
There’s not really any substitute for BIG drivers and LOTS of them! The most “you are there” sounding speakers I’ve ever heard were a pair of Ezekiels; twin 15” woofers, twin 10” mids, a three inch Mylar dome tweeter and one ultra-HF horn tweeter in each cabinet. With good audiophile grade vinyl, or reel-to-reel tapes; you literally couldn’t tell the difference from a live performance. We used to go hear Steeleye Span and the Seldom Scene at local DC clubs all the time.  The sound was IDENTICAL!
MC give it a break, you never even heard the op’s speakers. The OP wants to get a different speaker and yes, they will be much better than what he currently has, it won’t take much. You don’t need large drivers to get big sound. Some of the best sounding speakers use multiple smaller woofers to get full sound. For example, look at raidho, revel salon 2’s/studio 2’s, and others. 
I don't listen to orchestral works often, but my little KEF Reference 1 monitors create a bigger soundstage and image better than any of the much larger speakers I've owned. Combining them with four subwoofers doesn't hurt either. 
I'll mention another element. Right amp makes speakers sound good and big ! Give speakers 'the current' !