I have an Apple Airport Express as a source in my equipment rack that plays music and internet radio from a variety of computers. It seems that whatever "activity" I try to add in order to listen to the AE, I don't have a "source" that can play the material. My pre/pro is a Rotel RSP-1068 and it doesn't have a tuner, so "listen to Radio" is not working. I don't have a recognizable media server, so it won't let me pick a device I have. I am not quite sure what kind of device or activity to set up in order the choose the AE.

Thanks

Erik