Re: extending AV to 2 channel
The 1804 does have the ability for a dedicated zone 2. This is output via stereo analog RCA. Zone 2 can output any analog connected sources. For example, you cannot output the audio from a DVD player if you have it connected via the toslink or digital coaxial input. However, if you have the stereo analog cables connected from the player to the receiver as well that signal can be outputted via the stereo analog zone 2.
I would not run the analog stereo to another receiver if it is going to be over a long distance. Too much is lost for a receiver to amp it back up. But experiment. That is more fun than knowing exactly how to do it.