If your able...visit Ethan Winer's Introductory Acoustic Page.

Setting up some Owens 703 (Knauff 3lb) 4" thick in the corners as bass traps and some a 2" panel in the first reflection point will greatly increase your bass response, mids and highs.

This will not be overdamping a room by any stretch of the means. I would recommend these treatments only knowing that you haven't done them already.

This may actually end up saving you money on some less needed upgrades in the future. Of course you'll have to wrap the high denisity fiberglass in some fabric. Total price would be in the $130 area or so.

If you would like...it would also be easy to wrap the fabric and leave these panels as "portable" solutions as well. Only placing the corner traps in each corner...and using a single nail or some velcro for the first reflection panels. This way you can choose to take them down at any time...or leave them up

have fun!
dan