One setup I have seen that worked well had a thick rug on the floor (absorption), absorption in all the corners and along the top of the wall near the ceiling join, and diffusion on the ceiling, the two side walls and behind the speakers.
Another pal has his room with dissimilar techniques on facing walls. He says never put diffusion facing diffusion, for example. If the room is quite small I would want to do more absorption than diffusion, though
Another pal has his room with dissimilar techniques on facing walls. He says never put diffusion facing diffusion, for example. If the room is quite small I would want to do more absorption than diffusion, though