If you have a Paradigm or PSB dealer nearby I highly recommend both with Yamaha. The newer Yamaha's are a vast improvement, no longer overly bright but still thin and detailed so match very well with a warm speaker like the above two. Personally of the brands you mentioned I would only give the Polks a shot but they are a bit too detailed for Yamaha IMO and I can't comment on H/K as I have never heard them [except my computer speakers]. A Yamaha/Paradigm combo makes a very good system. I don't know your budget but for the 1500 look at the Paradigm Monitor series and you'll find several excellent matches. In the Performance series you will find the Titan and Atom and both would work fine as surrounds. Good luck and enjoy your new Yamaha.