As an experiment try covering sections of the drapes with plastic sheeting or poly tarps.
You could even try paper/Xmas wrap (anything that won't absorb much).
https://www.tarpsplus.com/products/white-poly-tarps?variant=39757140197538
DeKay
Room Too Dead
Hello All,
I am looking for advice and ideas on how to condition my Home Theater room. I built the theater in my unfinished basement. The foundation walls are covered in insulation and vapor barrier. Instead of construction walls to cover them, I chose a "pipe and drape" to cover the walls. I believe that the room is too dead. It seems to affect overall soundstage in the midrange range. Does anybody have experience with this problem and ideas to add a little "excitement" to the room? Thank you all.