@brett66 - thanks, GIK sells a nice 17.5in X 17.5in (5in deep) diffusor I will be trying this fall. I’m going to place 2 on each side right behind the speakers. Although, this is technically my music room, the boss always weighs in on the treatments and I’m pacing myself. The ceiling cloud I hung while she was busy watching her favorite TV program. The GIK A4 2D is absorber w/ diffusor grate so I will try the skyline diffusors, then remove the grates to see how big a difference. Very easy to remove w/ just 4 small screws per treatment.
My ASC isothermal traps have a screen diffusor about 1/3 the circumference of the trap, marked by double button. Behind the speaker has diffusion; however, I’m going to try the GIK 23 diffusor and see how that works. I ‘m also rotating the tab to see about the trap diffusor affect.
 - 17.5in sq, not 18.5in sq.