Can you use Apple TV/Airport Express as remote speakers?

[Radioman]

Done a search, apologies if it's been answered before but can you use Apple TV or Airport Express as a remote feed for amp/speakers and I don't mean from iTunes I mean the system audio out? It seems such a basic request but I can't seem to find anything about it... Would be grateful for advice.

 

[Radioman]

OK, a bit more searching and I've answered my own question, Rogue Amoeba's Airfoil software does it. http://www.rogueamoeba.com/airfoil/