I like all the room treatments you got going and the CMU block for stands... nothing more "solid" than a concrete block. I put a ton of ATS sound panels in my room (mostly on the back wall) and two ATS "picture" sound panels on the front wall.... but I am thinking about doing a sound diffuser in the middle front wall, over the system. I have seen a bunch of videos about building your own diffusers... looks pretty easy, but time consuming to actually build.
