I would try hanging a curtain behind the speakers about three inches away from the wall. You want sheers or better yet a sheers with small holes in them. That will eliminate your muddy part likely. Very cheap to do it helps control the back wave ant the top end makes it much clear.
Budget amp that will give Magnepan 3.6Rs better depth of soundstage
I have 3.6Rs and using Emotiva UMC200 pre/proc and an Outlaw Audio 7100 in a 14 by 14 foot room. So I don't need to turn the volume up to massive levels. The amp will do 100 watts per channel into 8 ohms and 165 watts per channel into 4 ohms. I have been thinking of getting a separate two channel amp for the 3.6Rs. I have read that it takes lots of current to get the best soundstage with instrument placement and depth. I am getting wide soundstage and good sound, but the depth is somewhat muddied enough to not get instrument placement. I am looking for a two channel amp that will give me more of the potential of the 3.6Rs, but be able to be purchased for less that $750 used. Is there any amp that will be worth upgrading to for that kind of money or do I need a new pre/proc as well?