What makes speaker's sound big?

Nope! When I had my wharfedale diamond 225’s set up, prior to getting my tannoys, they more than filled the room with sound, imaged like crazy, with plenty of bass. The speakers often performed a disappearing act and sounds seemed to come from well beyond the speakers, as if emanating from beyond the sidewall! I Drove them with my marantz pm14s1 @ 90 watts. They are astonishingly good speakers for the money!! Bought them after reading Herb Reichert and Art Dudley’s review in stereophile. They were right! If i had to, for some reason, put them back into the system, I would not be sad. Now I drive tannoy eatons with my sugden a21se, and to be honest, they do not play louder, but sound a bit more fuller, more oomph or authority. Do they sound better? That is subjective, as It is more likely that they sound different. Mind you the sugden is only 30 watt class A and the tannoys are only 89 db. However, if I was to put the pm14s1 back in to drive the tannoys, they may play a bit louder. I honestly could care less, as I seldom play music at ear shattering levels. Quality, not quantity, at least in my small world.