Rook,
Just so you know, my room is about 16X14X7.5, so is quite a bit smaller than yours, but on my EP500 I can only get the volume up to about 2 out of 10 with the wife in the house, 3 out of 10 otherwise for movies and such and its already shaking the walls. I can't imagine needing the eP600 for a room your size other than going that extra few HZ below the audible spectrum for additional effect on extremely deep bass tracks in certain movies. Based on my experience, you will NOT need the extra power. I assume you also have no WAF factor to deal with to have a fridge sized subwoofer in your room. My wife barely accepts my EP500, and its tiny compared to the 600.
