im experiencing brightness and would like some tips to treat my room.

i live in an apartment. room is aprox 15' wide x12' deep x 8' high. the right side opens to the kitchen. the left side is a large plate glass window with blinds. the floor is basically indoor outdoor. its like basement carpet over concrete. and the back wall is pretty much empty drywall.

incase you need to know my system is as follows.
FRONT: ascend accoustics CBM-170 SE'S
CENTER: ascend accoustics CMT-340 C SE
SURROUND: None (ascend accoustics HTM-200s soon)
SUB: Hsu STF-2
REC: Pioneer VSX-514


what could i do to treat my room? id imagine a large rug and thick curtains would help. any info would be much appreciated.

thanks,
andrew