How close do you have your speakers to the back wall? Do you have flexibility to try pulling them out further into the room? That usually helps a lot if you haven't already tried it, and it's free!!!
You might also consider some kind of bass management system like DSpeaker Anti-mode 2.0. There's one available here now for $599 -- much cheaper than buying new speakers and will definitely fix your bass issues. Best of luck.
You might also consider some kind of bass management system like DSpeaker Anti-mode 2.0. There's one available here now for $599 -- much cheaper than buying new speakers and will definitely fix your bass issues. Best of luck.