Using Airport Express pair as 'audio tunnel'? I'm looking to do something that I think is fairly basic, but I'm not aware of whether Airport Express hardware supports this scenario.  Basically, I just want to tunnel audio via IP packets / my home network, from a home theater, to a set of outdoor speakers.  [For the scenario, think:  being able to follow the action of a sports broadcast when I go from home-theater room, to outside my house, where my outdoor speakers are.]

If a pair of Airport Expresses can be configured as a 'dedicated, point-to-point audio bridge' then it seems like it'd work.  In other words - set up to just tunnel the audio input from one Express, over regular home-network IP, to the other bridge, where it re-emerges via line-out as regular audio out. Can those devices operate that way?  If not - is there an inexpensive way to enable?

I'm not aware of any 'bridge' device pairs that tunnel audio over IP (TCP or UDP) from a 'transmitter' to a 'receiver.' (Devices like this exist for Bluetooth... but, I need to span a large distance, and figure I should be able to leverage the my wired/WiFi home network to achieve this, and not worry about audio quality; bluetooth profiles; signal strength - etc.)  

Note, the goal would be to set this up once - and then not control them or manage them, using Airplay or anything else, thereafter.

thoughts?
The Airport does not have an Audio Input. It's audio-feature is essentially being an AirPlay receiver. Your plan will only work when playing your source material from a device that supports AirPlay.