I just bought a new Samsung 50" plasma TV and a Sony STR-DG720 7.1 recvr. I currently have a sub woofer and center channel. I'm looking to buy satellite speakers. Question....can I use my (2) existing floor standing polk audio speakers for my front channels and purchase some cheaper (4) satellites for the sides and rear speakers? Will the sound be messed up or will it work? Your thoughts please??