I plan to buy a Onkyo txsr601 and I have a Polk psw404 sub on the way. Can I mix a Klipsch quintet set with these or is it best to wait for the Polk rm6700 set?
You should be fine. The great thing about a subwoofer is that you don't need to voice match it to the main speakers. That is why there is a proliferation of independent subwoofer makers in the market