I have Klipsch 5.5 speakers and I currently use an 20 yr old Kenwood KR-920(B) 50 watts pr channel receiver. I plan to look at center channel speakers next and a new 6.1 channel receiver. Should I stay with same brand speakers? What should I look for in speakers? Any recommendations on center channel speakers? How much power should I plan on purchasing in my receiver to get to 6.1 system with good sound out of compatible Klipsch speakers?