Don't buy anything. Play with speaker positioning and your listening spot. 10 ft seems to be a bit far considering the distance between your speakers.. maybe you need to mitigate the reflectivity of the glass areas with some sort of absorbent material. I have found that speaker position and listening chair position have a real effect on sound and it's easy and free to correct. My speakers are 68" apart, and I sit 8 ft away. I just did this yesterday. I was about 9 ft back before. I will listen for a few weeks and move my chair again until I get it perfect, but it sounds much better than it did. When I look at my speakers from my chair,I cannot see the sides of the speakers. I also use a laser pen to see exactly where the speakers are pointed. Do the easy and free first!
Cheers
Cheers