I don't know that the wall unit is that much of an issue depending on design as it is a decent ways back, but the less reflective objects in it the better (if you have a TV, try to get a blanket or the like to cover the screen during critical listening). With regard to the nearfield listening position you will likely have to treat the first reflection points. I recently redid my living room to push my listening position from 7' back (equilateral triangle with speakers) to 9' back and it made a *huge* difference. In either case, try something like Echo Busters Double Busters MK II as they can be set up to be mobile to make sure there are no waf issues or if to be left in place can be ordered in a variety of colors.
ROOM ACOUSTIC ADVICE NEEDED
I have 2 acoustic problems dictated by decor: 1-An 8' wide wall unit between, and 4-5" behind, speakers, and 2-Near-field listening position (5-6') forced by dining island behind sofa-(my full range dynamic speakers with ribbon tweeter coaleses at more like 8-10'.) What can I do to control the acoustics?