Nsgarch is on the right track but adding that much absorption will tend to make your room sound dead.
If you treat the corners of the room with Eighth Nerve products you will hear a major change. They make the corners disappear sonically, in effect making your room appear to be larger. They are coming out with a second generation of this product soon but the ones on the website work very well for not much money.
If you treat the corners of the room with Eighth Nerve products you will hear a major change. They make the corners disappear sonically, in effect making your room appear to be larger. They are coming out with a second generation of this product soon but the ones on the website work very well for not much money.