I have all my media files (music, movies, etc.) stored on a NAS and linked into the iTunes library on eatch Mac. So, there is no need to run a complete, energy consuming server and a client to listen to music.
If it would be possible that the Apple TV 2gen access now the media, it would be easy to listen to music just by attaching an Apple TV 2gen to the HiFi equipment and no computer would be needed
So, all what would be needed, is a copy of the iTunes mediathek files on the Apple TV 2gen.
Would that be possible?
Copying the mediathek from a computer to the Apple TV 2gen could be done by ssh or any other network service.
(The NAS runs anyway (25 watts max. incl. Raid mirroring), and the Apple TV 2gen takes less than 5 watts. That’s much less than a running streming server itself and much cheaper in addition (my NAS wth 1TB hd and Raid-HD was total less 2/3 of a mac mini.)