audiodreamer, is it possible that you have your "Monitor Out" setting on your Onkyo to "Analog"? - in which case it won't accept HDMI for upconversion. Just a guess, but I can tell you with certainty that my 876 upconverts anything I feed it via HDMI.
The 876 is different, it does upconvert over the HDMI signal. I'll go find the article, I don't want to mislead you if I just misread the review, but I thought this was the case that the 806 would pass on the original over HDMI but not upconvert it. I'll get back to everyone with the review I'm thinking of.
!EDIT!: My apologies to everyone. I was confused. I had been considering the Onkyo and read a bunch of reviewes and confused them. It was actually the Denon that had this problem. No HDMI upscale
The problem with the Onkyo 806 only the issue of no pure pass-through over HDMI. Onkyo 806 HDMI pass-through
Sorry for the confusion.