Based on the excellent information provided here, I'm probably going to stay in the two-channel audio world for now. I'm considering two M2200's to replace my dying Adcom amp or I've toyed with the idea of something like the NAD c372 to replace both Adcom components.

If I do stay in the audio-only world, the Squeezebox or perhaps the Sonos (depending on the quality of the DAC) will make more sense than Apple TV. It seems that both the Squeezebox and Sonos work well with an itunes library, aside from the (current) inability to play protected aac files.