Basement listening room with large openings to other rooms-Acoustics Forum-Acoustic Fields Forum

I have a 2-channel listening room in my basement that I am trying to acoustically treat. The primary dimensions of the room are 14′ by 20.75′ by 7.5′ but, unfortunately, the room is not symmetric. One of the short walls has a 8.3′ opening and one of the long walls has a 9′ opening. Both of these openings go to other rooms within the basement.

Because of these openings, there is no way I can place my speakers in such a way that side wall reflections to the listening position are the same for both left and right speakers (i.e. one of them will always “reflect” into another room in my basement). I had my 30 minute analysis with Dennis and his first comment was that I violated this cardinal rule of symmetric speaker placement (resulting in reflection smearing).

What can I do (short of filling in the openings with new room partitions /drywall)?

One thought was placing ACDA devices in the openings to enclose the room. They would be on casters so that they could be moved when necessary. If I do this, do I need to place ACDA devices on the opposing wall (so that symmetry is obtained)?

Any other ideas?