There are a number of quick and relatively inexpensive things you can do. First, review the posts on the Room Acoustics forum (sponsored by Rives Audio) over on Audio Asylum. Good stuff there. Then read all/most of the stuff on Ethen Winer's and Rives Audio's sites.
You can start trying some of Jon Risch's "down and dirty" bass traps, which are essentially just bags of rolled insulation stacked in the corners of the room. Not pretty, but they can give you a hint of what can happen with a little treatment. I would also look at doing something to treat the first reflections points of your room. The best way to do this is with some simple DIY absorbers made of Owens Corning rigid fiberglass. See Ethan's site for more on this.
I've made a number of bass traps and absorbers based on some of the DIY designs and heard a huge difference in the sound. IMO, room treatment is a major factor that must be addressed before you can get the most out of your system
You can start trying some of Jon Risch's "down and dirty" bass traps, which are essentially just bags of rolled insulation stacked in the corners of the room. Not pretty, but they can give you a hint of what can happen with a little treatment. I would also look at doing something to treat the first reflections points of your room. The best way to do this is with some simple DIY absorbers made of Owens Corning rigid fiberglass. See Ethan's site for more on this.
I've made a number of bass traps and absorbers based on some of the DIY designs and heard a huge difference in the sound. IMO, room treatment is a major factor that must be addressed before you can get the most out of your system