Make sure your listening chair/sofa is as far from the wall behind you as possible. A lot of the reflective glare you're hearing is coming from that rear wall and the farther your ears are from it, the better. Also get the speakers in from the rear (the one behind speakers) and side walls as much as possible.
I have an 11 x 13.5 room and by doing this the glare has been reduced substantially. My ears are 22" from the rear wall and I'm still 8' from center point between speakers. If you can do this and the relatively simple treatments discussed above, your problem should be pretty much under control - unless, of course, it's equipment related which I know you claim isn't the case. However, believe it or not, there are speakers, amps, cables, etc. that work better in small rooms.
I have an 11 x 13.5 room and by doing this the glare has been reduced substantially. My ears are 22" from the rear wall and I'm still 8' from center point between speakers. If you can do this and the relatively simple treatments discussed above, your problem should be pretty much under control - unless, of course, it's equipment related which I know you claim isn't the case. However, believe it or not, there are speakers, amps, cables, etc. that work better in small rooms.