I would look at Crispin Herrod-Taylor and Crookwood.
http://crookwood.com/audio-monitoring/
Crispin, among other things, was one of the original designers at Focusrite (the console) before moving on to SSL, then becoming his own company. They specialize in mastering consoles but also make monitoring consoles. We had him design and build multiple systems for our 9-room facility in 2004, all custom configurable and expandle as you need, all the way to Atmos. It's brilliantly designed and he can add just about any option you can think of.
Reasonably priced, too. Look him up.