I would do at least one full wall of auralex, preferably behind the listening seat. The key is to kill reflections and make your room acoustically bigger.
I had a room like that 12x11, with back fully treated, each side partially treated, center front wall treated, and two columns of foam (4ft tall/12" diameter) in the front wall corners... music was inaudible before treatment, and great after, with all sorts of big and small speakers.
I had a room like that 12x11, with back fully treated, each side partially treated, center front wall treated, and two columns of foam (4ft tall/12" diameter) in the front wall corners... music was inaudible before treatment, and great after, with all sorts of big and small speakers.