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'

I think I will try a pair Magneplanar 1.7i and a pair of gr research servo dipole subs

just to try something new 
OP - I am biased, but I think you will love the Maggie 1.7i speakers. I have them in my main system and I use the Maggie Base Panel with them to extend the bottom end. They create a soundstage in my room (18 ft by 23 ft with 9 ft ceiling) that is amazing. I push the 1.7i with the new Krell integrated amp (K300i) with no issues at all. I did biamp the base panel with the Son of Ampzilla amp- the more current the better for Magnapans. If you live near Greenville, SC you are more than welcome to come by for a listen!

@ mahgister  Well, my answer was a bit short and not really explained.  Obviously, EVERYONE knows that YOUR ROOM is the most important element of ANY sound system.

Having agreed to that (I hope), we can then discuss a version of physics and psycho-acoustics.  All I can tell you from my personal experience in owning a shop for many years and having the opportunity to LISTEN to pretty much every type and combination of speakers from most boxes to hybrids like the Mark Levinson HQD system (full disclosure: we made stands for that system for Levinson), Bob Fulton's "J" system, and so forth, and trying to understand why "good stuff" sounded less than good in many of my customer's rooms, I finally realized what Mr. Winey and others had been trying to explain to me.

1.  The ROOM is more important than the "stuff" you use.  This was made clear when various "high-end" manufacturers entertained me in their showrooms and showed me how good and bad the same stuff could sound when the room was changed around or things moved.
3.  Horns belong on the top of poles at high school football stadiums.
4.  Pure electrostatics will burn your ears out (listening fatigue) fairly quickly at any volume.

Once I HEARD all this, I realized, and then again yesterday when I turned on my system and listened for a while, that Maggies are in their own world regarding sound reproduction.  Perfect?  Don't be ridiculous.  Hard to position correctly for the best possible sound?  You know it.  Require lots of high-quality equipment?  Absolutely, as they reveal whatever you put into them.

So yes, a small room is harder to "Maggi-fi" than a big one, but it can be done by selecting the right gear and having a professional, like your dealer, I hope, set everything up for you.  May not be easy, and yes, some rooms simply do not work with them, but for the most part, you get the most accurate music reproduction from Maggies.

Don't believe me...hey, I realizes that flat-Earthers think the Mars landing is a fake...go listen yourself in the shop and THEN in your ROOM.  You might like what you hear!

1. The ROOM is more important than the "stuff" you use. This was made clear when various "high-end" manufacturers entertained me in their showrooms and showed me how good and bad the same stuff could sound when the room was changed around or things moved.
3. Horns belong on the top of poles at high school football stadiums.
4. Pure electrostatics will burn your ears out (listening fatigue) fairly quickly at any volume.
All your post will be very useful to others.....

thanks for that....

Only a small observation about your righfull remark that boxes distort the sound....

It is precisely the reason why especially with boxes speakers damping, isolation from vibrations and controlling internal resonance could give so much correction and compensation... It is precisely for that reason that ACTIVATING the room with the pressuring engines which are my 18 Helmholtz tubes and pipes compensate in some degree for this distortion.... Dont rectify it completely, but compensate for a specific pair of ears: mine....Musical timbre perception here is the key to feed back listenings experiments correction.....

Boxes are not perfect but could be very good for the price in a small room.... I succeeded...Cost of speakers: 50 dollars used....And i prefer my sound to some 250,000 dollars system i listen to on youtube where the room is catastrophic and nobody ever even has been conscious of this fact ....

I dont say that my speakers are better, not at all, they are trash compared to costly one, but in a controlled room they can be on par with anything very costly which is working in a non controlled room .... People cannot imagine what are acoustic laws and why they are so powerful....At best they imagine sound waves bouncing from the passive walls....It is way more complex than that... The audio superstition in the market speak the language of electronic design and his measuring concepts, the upgrading motto...This is half-truth....Worst than a lie ....

Being audiophile is more linked to acoustic consciousness than being obsessed by electronic design....All thread reflect the opposite... It is the main reason why so many people are frustrated and deceived by their system.... It was mine to begin with.... It is no more the case for me without any upgrade....

I concur with all your post....

It is very important that all those who reviewed gear in a room realize how futile it is to describe sound that make sense only for their specific ears...

It is very important that people realize that upgrading BEFORE controlling and activating a room is throwing money to sellers that dont care about  audiophile experience and the installation of a system in his 3 working dimensions but about their products first and it is normal....Anything anormal here....It is the duty of people to educate themselves in the way to install any gear in a room....

My best to you.....

Mahgister, I appreciate all the comments and think you are very correct that most of us don't fully appreciate correct room treatments, etc.

The most stunning demonstration I ever heard was at RMAF when one of the Brit reviewers did a session on equipment isolation and good stands. They also had four (2'x4' ?) Helmholtz resonator panels set for all four walls. The Wilson Audio Duettes? were stunningly set and sounded superb with the system sorted.

When the reviewer and the other guy pulled all four stands out of the room the 30+ people inside were stunned at the total collapse of what we had all just heard. Sure, there was music; but the difference was off the charts (worse).  Then they put the resonator panels back and the music came back. It was aurally incredible! No tricks, no stunts.

Sadly I've not had the patience or knowledge to recreate this in my room although I feel it is very room dependent in terms of the individual design, much like it seems your brick and pipe devices are designed.