New to this site and I appreciate any help you can offer to improve fullness of sound. I have Definitive Technology 5.1 (small surrounds). While the sound quality is quite good the small speakers lack the fullness that you get from larger speakers. How could I gain more room-filling sound. Tower speakers are not an option for this room. Do I need to replace front speakers with larger bookshelf speakers? Should I upgrade receiver to achieve a configuration that allows center, large R & L front speakers,4 surrounds and a sub? If so, what receiver would allow this configuration.? I assume larger bookshelf speakers should be Definitive Technology? Thanks for any recommendations