I am assembling a new home theater setup from vintage Polks found on eBay or craigslist. Here is what I have so far: receiver - Sony STR-DA4ES. Speakers - surrounds FX300i, subwoofer PSW120, and currently using R1's as fronts. For the center I have an M series center, but prefer my Boston Acoustics CR-1 better. Would my setup benefit from some better front channel Polks? I have three FX300i, would I benefit by getting another FX300i for a 7.1 setup? Thanks for the advice.