Room treatment is specific to the room. What you want is well damped room modes and reduced early reflections. The directivity and orientation of the speakers helps reduce early reflections but if you have a lively room, you can always add absorbing or diffracting surfaces. Framed drywall construction helps damp room modes but if you have rigid walls, you might want to add panel dampers. Adding subs also helps, as the more bass sound sources you have, the more the modal region is smoothed via dense interference.