Bryan,
I took down the 242s and moved one behind the listening chair up above the doorwall.
BIG difference (as in immediately noticeable) right off

I found a pair of discounted Auralex SonoSuede corner panels that I am going to mount on the sidewall/ceiling corners flanking the chair.
I finished the first diffusor array and it is not as noticeable as the 242 in the rear corner...
maybe more will help?