A buddy has a 7.1 HT with Klipsch quintets (going on memory), a Klipsch sub-woofer and KG4 fronts. He likes his system, he is not an audiophile so to speak, but watches blue ray, listens to CDs and vinyl, and wants to upgrade his center speaker and get something better than the quintet center. Does anyone have a suggestion for him for a better used center speaker? Budget is somewhere around several hundred max. Thanks in advance for any suggestions.