In my experience, the word "involving" is typically attributable to the speaker/room placement. Because of the other soundstage type problems you mentioned, I think this is the place to start.
My room is much smaller, but I've had movements as small as a couple inches affect what I characterize as "involving". You may want to start by trying a closer listening position and/or different toe-in.
The other culprit could be the pre-amp/amp impedance matching thing mentioned previously. Call the manufacturers of your equipment and tell them the problem and associated equipment. They will know infinitely more than probably anyone on this board about how your equipment may be interacting. Good luck.
My room is much smaller, but I've had movements as small as a couple inches affect what I characterize as "involving". You may want to start by trying a closer listening position and/or different toe-in.
The other culprit could be the pre-amp/amp impedance matching thing mentioned previously. Call the manufacturers of your equipment and tell them the problem and associated equipment. They will know infinitely more than probably anyone on this board about how your equipment may be interacting. Good luck.