Hi all,
Bridgman's, JohnK's and Chesseroo's contributions are all useful but left out of this discussion is the simple fact that "filling the room" is really a euphemism for distortion levels as small drivers (and fewer of them) in smaller speakers have to work harder--much harder--to achieve satisfying SPLs in bigger rooms than do big multi-driver speakers.
As the small driver's excursion increases it becomes non-linear as the voice coil moves out of the magnetic gap, and distortion rises. A small speaker may begin to sound "edgy" or "congested" when it's driven beyond its limits (these are terms we used in double-blind tests of speakers, small and large) and that's what you risk when you put small compact speakers in very large rooms.
This also relates very closely to preferred loudness levels--and that can vary significantly from one person to the next.
What we can't know at Axiom is exactly what volume levels a listener prefers and the degree of absorbency or reflectivity of the listening room. So I believe "filling the room" is a kind of insurance against the potential of a listener trying to force compact speakers to reproduce very high SPLs in a big room. We know the M60 and M80 will do that and that they'll sound clean at very loud levels. Colleagues of mine often listen at levels 10 dB or more louder than I prefer, (and that is the more common scenario) with peak levels well above 100 dB SPL at the listening area.
I don't care whether customers want music "louder than life"--it can be thrilling, I know; I just want the speakers to be able to do it and still sound really clean. Besides, even "louder than life" has very different meanings. If someone frequented discoteques or heavy-metal concerts and got used to 100 dB-plus levels all the time, then that's his reference. It isn't louder than life to him or her.
Regards,
