What makes speaker's sound big?

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.

Thanks for you kind appreciation...

I thank you for your post that will remind all readers that NO upggrade can replace the powerful controls in the three working embeddings dimensions of any audio system... Especially the acoustical one...

By the way it is possible to replicate what you listen to at no cost.... It takes only time for listenings experiments.... It is way better than to boast about a 100,000 bucks amplifier like some reviews did.... 😊

Accurate frequency response AND coherent phase from 17hz to 30khz and listen at reference volume. 

Result: BIG SOUND. 

One does not need large speakers to achieve big sound and throw an immense, deep soundstage that goes on forever. But the room size matters, distance to the speakers, room treatments as well as the specific drivers for spl potential. That's why to get the above, larger speakers are often needed for large rooms. 

Can you ditch the DDs and get that in your room? If your room is fairly lively, undamped and you can sit close, yep. Obviously, not without subs and expensive speakers. 

Not having read every response I would say that the amplifier has a hell of a lot to do with the sound..

That's what I said - the amp. Speakers should be reasonably good, of course.