the receiver i have is a http://gdgt.com/sony/str-k670p/specs/. i wanted to replace two of the speakers it came with and get two http://www.polkaudio.com/products/monitor50 and replace the center speaker and get http://www.polkaudio.com/products/cs2. can anyone tell me if these 3 speakers are compatible with my receiver? thanks!
Your receiver will work fine. The link to the center channel goes to an error page but it looks like the matching center to the front towers is the Monitor 15c. http://www.polkaudio.com/products/monitor15c
It is important that the front three speakers are voiced to work together.