Honestly to get the optimum would be something up into the 800-1000 square ft room... no joke, a good 18ft - 24 ft wide by 30ft -40 ft deep... this is where they would open up for real and be like walking into a theater... but with the small room problem which is the same problem I have, I must have them 17.5" at the back to the sidewall and 19.5" in the front from the sidewall(Angle toe in if this makes sense) my room is 14 ft wide, otherwise I lose a ton of Scale and weight in the music especially voice... Beyond that I was running them 28" of the backwall and this was because I wanted maximum bass responce without having to crank the internal amp, but took a shot at moving them 36"(3ft) and gained far more real impact and bass responce, my backwall totally ate them up and made a distorted boomy sound if they were to close to it... They then ended up 34" out from the back to get just a slight more deep bass responce in my room than the 36" did, I think this is because I have a door open almost directly behind my left speaker and too far out bleed more room pressure... Now I listen at Incredible Dynamic and powerfull bass levels, think about the guy with the annoying cadilac on the street, I must have viceral feel and impact and no way could these breath enough with a total of 8 10" woofers less than 2ft away from the backwall in my room without making a distorted mess, and sound like something is slapping and ringing behind the speaker. Again this could all be very room dependent, where are the openings, and if you put some money into room treatments.