I just bought Klipsch HD-500 speakers and now I am looking for a receiver. Ive narrowed my choices to the Onkyo TX-SR607 and Onkyo TX-SR707. The 707 model is the next level up but also a few hundred dollars more. I have a medium size living room with a 50 in Plasma, Blue Ray and my 5.1 Klipsch speakers. My questions are, is there a big difference between the 607 and 707 receiver? If so, what are the main differences and is it worth a few hundred dollars? Any additional info would be very helpful and much appreciated. Thanks!