Congradulations on the new AVR!!!
The SC-37 is one of the best recievers that you could have purchased to date PERIOD!!
I hope you were able to sit down & listen to at least a few recievers hooked up to the B&Ws b4 you made your buy. But either way I can tell you from experience that the PIO will really make those 683 sing & dance! The classD amps really hold up to their power ratings, even with 5 channels being driven, so dynamics will never be short. Since the 683 dip down to 3.2ohm occasionally, you need power with balls & that AVR has plenty!
I have a very similar setup as you can see from my signature below. I was actually dead set on either the new Denon 4311 or Pio SC-37. Then I came across the Yamaha & to my suprise I LOVED what it did to the 683s. There is something about how different components work together, "synergy" as some call it. But i tell you that the SC-37 does an incredible job & if i wasnt planning on getting a seperate power amp down the line to increase the usable power the Yamaha puts out, then the SC-37 would be at my place too!
ENJOY,ENJOY,ENJOY!!!!
Im a huge fan of Bowers&Wilkins, have owned a number of their speakers & will probably always have something of theirs no matter what else i get into.
Post some pics when you get a chance!!