Happy New year Spencer. I'm still getting use to this Northwest weather, quite different from that of the California desert I spent six years in before moving up here. Everything is frozen in the morning! It's dark and cool all day during the Fall and Winter, which I'm really enjoying after being in blinding light and heat for six years. No more skin cancers! I've spent a lot of time on California beaches, and have paid the price.
I bought a nice piece of 1/2" X 2' X 4' plywood and cut it in four equal pieces 6" wide, from which a 6" deep frame measuring 4' square can be assembled. I then got a bag of Roxul Safe 'n' Sound, which contains twelve 3" thick pieces almost 16" wide and 48" long. Three pieces fit inside the frame, and two layers completely fill the frame's 6" depth. Perfect! One bag is just enough to make two absorptive panels, one of which I will position on the wall right behind my listening chair. I'll place the frame on top of a pair 9" Tube Traps butted up against that wall, and the combination of the Traps and panel should mitigate both reflections off the wall and the bass mode (present in all rooms at wall/ceiling/floor boundaries) at the listening position. I haven't done it yet, but Spring isn't that far away ;-) .