Two areas need to be addressed. The first is speaker placement including toe in. We have a tutorial on our site at the http://www.rivesaudio.com/listroom. Go to speaker placement and you can download a short white paper on some of our philosophies about speaker placement.
The second area is room acoustics. Quite often they are out of balance. Midrange frequencies need some diffusion to keep from having the glare you mention. High frequencies are often covered nicely by carpet, drapes, and other furnishings, but most of these do little for mid frequencies. The problem comes when you try to get this in balance, because most of the time when you try to absorb or diffuse mid frequencies you almost always attenuate high frequencies. If the highs were previously correct, they will become over damped, and the room will still sound bad (but different). Not knowing much about the room, it's difficult for me to comment further, but hopefully these ideas will help.
The second area is room acoustics. Quite often they are out of balance. Midrange frequencies need some diffusion to keep from having the glare you mention. High frequencies are often covered nicely by carpet, drapes, and other furnishings, but most of these do little for mid frequencies. The problem comes when you try to get this in balance, because most of the time when you try to absorb or diffuse mid frequencies you almost always attenuate high frequencies. If the highs were previously correct, they will become over damped, and the room will still sound bad (but different). Not knowing much about the room, it's difficult for me to comment further, but hopefully these ideas will help.