I have a 50.4, & I had a no audio situation but I only had to switch to another input via remote like going from game 1 to game 2 then back & it works fine. The issue only happened a couple of times in the last 2yrs I've had the receiver.
My Onkyo one he other hand,(805),started doing that same thing then the HDMI board went completely bad, per Onkyo Authorized Repair Service. I hope his isn't a sign of the dreaded HDMI issue. I have kept in contact with the Dealer\Repair shop & as of today, they haven't had an HDMI related failure repaired or reported. I hope you just had some type of HDMI interruption that just needed to be reset or something. The input that had the audio drop on my 50.4 was from a HDMI over CAT connection & I know sometimes that can get interrupted from the powered side of the converter. I once unplugged the converter & plugged it back up & it recycled, but I won't do that again unless I power down the unit so not to cause a spike across the HDMI board.
I truly hope your problem is just some simple glitch. Please keep us informed.
Last edited by G I Joe; 01-13-2015 at 05:56 PM.