Room treaments

I have a theater room your size.  I added 4x8 wall panels from 4seating.com.  I have plush carpet on the floor and nothing on the ceilings.  Believe it or not it is almost to much.  It is great for the theater room but not for a two channel room.
I just added cinema round panels from Vicoustic Acoustics in my very large great room where my two channel area is.  My room is 25'w by 40'L with 16' ceilings.  Just adding 4 2'x8' cinema round panels helped my room substantially.  Vicoustic provided a whole analsis of my room after providing them a video.  I have used GIK and Audiomute.  With your low ceilings, I don't think you will need that much.  Do it in stages....see how it sounds.  

Reach out to GIK Acoustics for one on one free consultation. Once they make their recommendations, do it in stages. I did my room in three phases! 

I love GIK.


From what I’m reading I suggest the following: More diffusion and don’t ignore the floor between/behind the speakers. Lot of hash lives there.

Do bass traps carefully. You can overdamp, leaving you with a lean system, but smoothing out the response is critical to a good system. If you can measure as you go you’ll be in a better place.

If you have no bass resonances, or well controlled one's you are done.

Best,

Erik

GIK is excellent, but I'm using Vicoustic now. Check them out before making your decision. https://vicoustic.com

The ' corner bass traps ' floor to ceiling may introduce issues in terms of balance.
Tackling 20 - 200 Hz will be the most difficult but a relatively low reduction in level should be smooth enough.
Absorption behind the ' mains ' should help a bit as well.
My sense of a rooms ' sound ' tells me that diffusion on the side walls could be a better solution than absorption.
Even absorption on one side and diffusion on the opposite wall at first reflection points - ' A Symmetric ' could be effective.