Thanks for help a year ago re: resetting the firmware by pushing VIDEO6 and SOURCE. I have had to do that 3-4 times, and after the most recent one, I had 2 problems: 1) It changed some Input Settings (COAX3 to Optical 1), which I just changed back today, and 2) I have STEREO as the ONLY LISTENING MODE!?!
I've tried pressing the "surr. mode" button on the remote, and physically pressing the "surround mode" button on the unit, and the only option is STEREO. When I try and scroll through the onscreen menu, there are NO OTHER OPTIONS! In the past I've used EARS, etc. , and can see the LED lights search for those modes when starting up a DVD, but I can never scroll and get options other than STEREO.
Any thoughts? No sound is coming through center or any rears (Sub - yes, but that has a separate "on" toggle on the menu.)
Since it is the weekend might not hurt to check to see if the unit defaulted to a two speaker set up. If it has, correct it to the proper speaker configuration and it should then present you with the options you had before.
To me, this sounds like the 753's RAM is having problems keeping its settings so this is not just a firmware issue - I suspect hardware. Call NAD or your dealer.