Consider swapping the cabinet and the audio and turn your couch towards that wall. You have very unbalanced side reflections that will hurt imaging and your couch is mid-room. Rotating should change the boundary issues. Given the equipment, it is a room issue so this change my be the least dramatic change in terms of cost.

Test run it with a just the AVR and speakers to see if it is better.

Panny 3000 PJ, 118" Carada, Denon 3300, PS3, Axiom QS8, PSB 5T, B&W sub, levitating speaker wire