You gotta get over to Ethan Winer website & forums and start readin...John Sayer has some good stuff too and there's a forum here about acoustics or studio building as well.
Basically you just have to figure out how to determine where your speakers will perform best in your room at your optimal listening levels. How much early reflection, ambience, and bass trapping you want to add.
The monitors themselves will provide most of the 'coloration' for the mids, the room [of the sizes you're talking] will 'mostly' be responsible for the bass and the ambience/reflections.
There's a way to walk around your room, play tones or a familiar test CD or reference, and determine where the best balance for the speakers and listening position is. I didn't do that - I just went out and got ETF software to give me the data I needed to do that...even though the software is pretty good once you figure it out, oddly enough it has a DOS kind of feel to it. In this age of GUIs and stuff I expected an updated version - maybe one will come out.
So then - maybe the point is to get some reference CD's and play them on your new set up. Change your speaker position and listening position to where things sound the best, then do that again (moving everything) 5 or 6 times and you'll probably get it correct.
I think there's a clap test you can do for reflections, like I said I use ETF so I put foam up untill my RT60 dropped below 400ms - it didn't sound good under that but at the same time Ethan has some goon info about early reflections on his site somewhaere - I'd read that.
This is my 4th acoustic set up and although it's pretty good I still have some 'earlies' I gotta nail. My speakers are right up against the wall to get the smoothest bass response (Event ASP8s) and that kind of surprised me. If I had my way I'd probably be in a room with 30 foot ceilings and about 40x22, hehe next lifetime.
I'm in an attic room that has been remodeld, the house has a steep pitch on the roof so I think that some of the bass passed directly out the drywall into the attic instead of cloggin up the room with so many standing waves down in the bass region. If was downstairs or in the basement where there are more effective barriers and boundaries beyond the drywall then I might have more problems than my rigged up bass trapping could handle (couch & fibreglass).
