looks like i'm having the same issue with my 609. getting no sound at all from analog or digital sources. i've been in contact with onkyo and it seems they're willing to do an out-of-warranty repair. they hinted that this is a common problem. they haven't responded to my emails for a few days. they said the repair would take 2-3 weeks, but i've heard about people waiting a couple months to get their receiver back and sometimes it's not even fixed. i can't sit around with my theater room out of commission for that long. the longest i'd be willing to wait is about 4 weeks, which is when the ps4 comes out.
unfortunately, i'm pretty cash strapped at the moment and i don't want to buy a replacement if i don't have to. i've been looking at the 616, but it seems like it has more problems that these models. i'm leaning towards the Yamaha RX-V673, but again, i don't wanna buy anything if onkyo can fix mine in a reasonable amount of time. what to do, what to do.
COSTCO has a great return policy... you could buy then return in 90 days or less.