I would like this also. But do not know if any AVR's do this. Although I have asked some questions about it nobody has offered an alternative.
I can only assume it can be done via a HDMI switcher if you have just one HDMI on the tv.
Afraid to ask though cause most people will say "why do you want to listen to the tv speakers."
But I have noticed Im not the only one who wishes to do this.
My tv has 3 HDMI in.
Assuming that I could use a HDMI from cablebox to tv to do this.
Then another HDMI from AVR to tv to play sources.
Only other thing I would like is to play PS3 with AVR on or AVR off.
Thinking I could get this done with HDMI switcher?
Im also considering the 1909.