I'm trying to set up my Apple TV in my studio so I can listen to my music that is on my iMac in my office next door. Can't I do it directly through my WiFi without using iCloud? I don't want to get involved with iCloud.
Apple TV
You don't need iCloud unless you want to use iTunes Match to stream your library directly from the cloud.
To stream music off your iMac you simply use home-sharing. The computer would just need to be on and running iTunes in order to access over the local network.
http://support.apple.com/kb/HT4620
Do I need iCloud to share my iMac music with AppleTV?
