It sounds like you've overdampened your room. Try removing the existing room treatments a piece at a time until you start to get the level of ambience you desire. Once you're in the ballpark, then you might want to experiment with different type of products. Most rooms require both dampening and diffusion. Typically, the first reflection point requires a dampening type product. The spot directly behind the listener and the ceiling reflection points require diffusion. Unfortunately, there are no hard and fast rules and extensive experimentation is your best bet. However, be careful not to confuse phasiness with the spaciousness you desire. Try using a mono source. Perfect pinpoint mono equates to a proper stereo image.
Listening Room: Diffusion vs. Absorption
I am setting up a dedicated listening room and have been looking at different acoustic treatments. Currently, the 12"x17" room is highly reflective, and actually hurt my hears when my system is played at any decent volume, I stapled Fiberglas insulation at appropriate points in the room and my ears no longer hurt but the room sounds dead, w/ no ambience. I had been planning to use acoustic foam to dampen reflection but am now thinking about solving my problems by using diffusors. Anyone have any experience in this area? Will appropriate use of diffusors give the room more ambiance? Any experience with RPG Diffusor Systems or their BAD Panel, Omniffusor, or Skyline systems?