B&W DM603 S3's

I'd like to ask anyone who has the above as their main (surround sound) or only speakers (2-channel) what size room are they in and where do you have them placed? How far apart do you have them? If you have a SS system, what are your other speakers, sub, etc? I'm just trying to compare to see if I can make any tweaks or improvements to my set up. Many thanks.
I have a pair of 603 S3's in a room about 12 X 15. I use them in a 2-channel set-up as the main speakers. I tried driving them with several different tube amps and I did not like the sound. The cabinets seemed to be too active and resonate on the midrange. I read somewhere that they like alot of solid state power so I tried an Adcom 5500 - much better. Room placement is no longer as critical and sound is clean.