I had serious problems with piercing upper midrange glare in an untreated room with my Focal 936's. A doubt Dynamat is better than rubber backed carpet which was my first solution. It was inadequate. I resorted to 12"X12"X2" acoustic foam panels. 36 sq/ft spread across the wall behind my chair. That stuff got the job done well for about $50 on Amazon.
Dynamat, if I'm thinking of the right stuff, is designed to keep large areas of sheet metal from resonating. I don't think it'll serve your needs well. You definitely want to kill those first reflection surfaces and I'd start with the biggest one right behind you. Diffusion is a useful tool as well, and if you have the tools and facilities to make some diffusers you may want to try that. They're useful for softening the sound rather than just sucking it out of the space. Diffusers are especially useful behind and between the speakers assuming the speakers themselves are well balanced.
Dynamat, if I'm thinking of the right stuff, is designed to keep large areas of sheet metal from resonating. I don't think it'll serve your needs well. You definitely want to kill those first reflection surfaces and I'd start with the biggest one right behind you. Diffusion is a useful tool as well, and if you have the tools and facilities to make some diffusers you may want to try that. They're useful for softening the sound rather than just sucking it out of the space. Diffusers are especially useful behind and between the speakers assuming the speakers themselves are well balanced.