i own a pair of magnepan 1.6 and recently acquired a pair of quads unlimited quad 57s.
i am the speakers toward the side walls, which are treated with a sound-absorbing material, in order to change the frequency response. since there is some absorption of the upper frequencies, i find the overall frequency response, closer to a balanced spectrum. of course, taste and preference are the issue here. try it and see what you hear. you can always move the speakers back to their former position.