My new Denon AVRX2400H sounds amazing except for the center channel speaker (Sony SS-CN5000P) which still sounds as bad (hollow and boxy) as on my old Sony receiver. I have tried turning the center channel off completely but do not like how that sounds either. I know the boxy sound of a center speaker is a common complaint but I was wondering if throwing more money at the problem like, say a Polk S35 would help any. My front speakers are in the "Big Advent" walnut enclosures from the mid 1970's but the woofers and tweeters were replaced about twenty years ago with parts from another manufacturer unknown to me (They still sound great!). Any advice would be appreciated.