It must be the handhsake that HDMI requires, without the return signal the oppo won't send a signal, I guess.
I agree with you. I have a Denon 2807 and Oppo 981 which also seem to have some HDMI handshake issues. The Oppo is hooked up to the Denon which is hooked up to the TV all with HDMI. I still get audio when playing a CD or DVD when the TV is turned off. However, if I change the TV input to or from HDMI while something is playing the audio drops out for a second like it’s renegotiating the exchange.