The good thing about the klipsch is that they are super effidient so you Onkyo receiver will have no problems driving them. I really like the Klipsch sound but some people don't. I have the same receiver and it does really well with the Klipsch. Just my 2cent...
I bought my receiver at onkyousa.com where they sell their factury refurb stuff. I didn't have have any problem with them. It is important to buy from a trustworthy source. Godd luck jonathan