Room size for large speakers?

My experience is that there is a dranatic improvement between "bedroom" sized rooms (12 by 14 feet) and rooms in the 20 foot range. After about 30 foot size you still get improvement but diminishing returns. Much greater than 50 feet becomes a problem becuase of large delayed reverb IMHO.

Of course as Rives correctly implies... a good treated small room may sound better than a bad untreated mid sized room...