New Mac Mini, AIrplay and sleep

I have a new Mac min on which I run iTunes, and access this using airplay on my Denon amp. All controlled with the remote app. Works well now, after some time of continual drop-outs. However, my Mac Mini refuses to sleep after having used the airplay function. If I don't use airplay, the Mini sleeps when it should do.
Anyone have any ideas?

The Airplay feature is going to keep your Mini awake. Try this first:

System Preferences, Energy Saver. Remove the check from the box that says: "Wake for Network Access". If that doesn't work or the check has already been removed, you may have to live with it unless someone else can come up with a solution.