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'

@mahgister --

Not necessarily completely true...

I own 7 inches speakers box 2 way, and the Brass orchestra filled my entire 13 feet square room with soundstage OUT of the speakers at the left and at the right and imaging 3-d with clear tuba notes and Horns...The brass orchestra is in my room....Not between the speakers in reduction.... The results is less related to my speakers themselves than to acoustic controls...

13 feet sq. room - so 13 ft. per wall? I don’t doubt speakers of the size you have fits the bill in providing such an acoustically well treated space with a big, immersive sound, but I’d claim that well-implemented subs would only add to that sensation. In the quoted part above I did emphasize a more authentic sense of sonic size, and for that I maintain a fairly large (acoustically well-treated) listening room and main speakers + subs is necessitated. Moreover, while the size of sound is typically associated with soundstage presentation, for good reason, it’s not the only parameter as that which fills the listening space with a more palpable, effortless sensation of sound. For that more displacement and headroom is needed - at least in my book, and depending again on the size of the listening room.

ACOUSTIC controls is way more important than speakers size in a small room and most of the times in a moderate bigger room...It is my experience only but.....

It is not raw power of the gear or mostly the size of the drivers mostly that makes event livelier but acoustic control of the room....

Audiophilia in general is very much focused on soundstage presentation, the virtues/characteristics of which you point out above, but I’m more interested in the particular type of presentation as this homogenous, large sweet-spot sphere of sound that’s visceral, full, present, effortless and less pinpoint sharp imaging-wise. To me at least it’s more reminiscent of a live event, and in that regard makes for a very effective association, or certainly one more complementing at that as something that has actual, believable size sonically.

That is to say: proper, not over-damped acoustics (and care with speaker placement) no doubt aids soundstage presentation and size in particular and as such fits many an audiophile’s "craving" here, but the fundamentals of sound with dynamics, presence, girth and ease, to my mind equally important as a constitutive measure with regard to the size and believability of sound, needs for physics to be accommodated. I’m not saying the latter should trump (no pun intended) the former, but that some coexistence is necessary here.
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I say olde chapPerhaps a double impact is a bit stiffCan go with a single?
If not then I recommend training