Absorbtion?

IMO your room is not too small. There are other issues at work here, synergy being the primary I believe.
Not sure where you're going with the 'glass' question but certainly it reflects. I had a pair of split glass doors on my heavy wooden component rack (which I very rarely closed anyway). One day the cats were roughhousing & banged hard into one open glass door, stripping out a hinge woodscrew. In the process of effecting a repair, I removed both doors from the rack. The rig was playing & as I was walking around the house I noticed an improvement (a reduction of midrange glare, which I had been trying to figure out for some time). Following some brief critical listening, we decided that those glass doors were never again going to be installed.

Thanks Bob, i have 2 critters myself, love em to death. The glass is wall to wall behind the speakers presently in L shaped room. Can't figure it out, should be more revealing uptop, its not! Would really like to try setting up in 11x16 room. Lot of pressure will be in that room with this system.

Hello Mikec, I also have an "L" shaped room. I'm set up in the corner of the "L". Also have an open stair in the corner. 16ft long x 12ft wide with a vaulted ceilng 8-12ft. Thiel CS5i's, Classe CA-400, ARC LS-15, MIT 330 med bal, 330 shotgun bal, 770 twin cvt. I devided the length by 5th's. So my speakers are a bit over 3ft from the wall. I sit in a leather sofa against the opposite wall, about 9ft away from them. The speakers are about 9ft apart. For these speakers, I guess that I'm in the near field. I had to work on toe in with the highs. But everything sounds great. The only treatment that I use is a throw rug on the wall behind my speakers. My dealer told me to be careful not to "over" treat the room. I also have wall to wall carpet with a throw rug in the center. An "L" shaped room can work, it just takes a lot of placement to get it right. You might want to borrow a tube pre from your dealer to try with your CA-300. Good luck!

Mikec:
Do you have treatment in first reflection points in the walls?
Is your ear level listening position the same as the 10 T tweeters?
Do you perceive better highs if you move back / forht or side to side / up down from your current listening position?
What´s your source / do you have rack? how about if you have spikes under CD player or power conditioning
More info might help to better understand what your situation is
Regards

10Ts are on the stands w/castors!. No points under anything. Frontend is Classe CDT-1 Trans into Classe Dac, Sony 7700, DD Satellite, Classe Tuner. Can't cornor load system in L. Tried moving head up-down-side-under my ass etc, same for speakers. Heads swivel on 10Ts. Am pointing one speaker more towards open L (does sound better this way). Maybe its my 50yr old abused hearing + room. I do have hearing loss for years now, maybe getting worse. I'am going to place system in 11x16x8 room. My experience and common sense lends me to believe it should work fine. If not i'll sell the 10Ts and try a smaller speaker for the smaller room. Would like to try a speaker with a Ribbon Tweeter. Any suggestions with Classe pre and amp. BTW after visiting the dealer and listening to a tubed AR preamp (?) and Pass X350 and 10T, i was shocked how Sterill Sounding and Bright the combo was. Maybe the AR pre was SS. Wasn't really interested in the electronics. Didn't like the sound at all. Maybe the 10T is not the speaker for me. This is my second pair of 10Ts. Need something more exciting. Ever since CD was intoduced the music just never sounded the same. Years ago just put a record on, look at the cover and jam. I just don't know anymore. Seems like all the manufactures are shooting for transparency and missing the involvement and emotion of the music. Same for most new material. Were are the singing guiters hiding? or the magnificent orchrastra in the background. Their not in my living room. Bet their hiding in Albert's living room!!!