Apple - Can I turn a Windows machine into an AirPlay destination?

If you only want to stream audio, try Airfoil Speakers, part of Airfoil for Windows

Here is a fast and simple open source program that works very well: http://sourceforge.net/projects/shairport4w/

Reflector 2 allows you to AirPlay audio and video from iOS to Windows. It claims to support iOS 9 now also (note I personally haven't tested the iOS 9 support yet).

Reflector installs an app that acts as an AirPlay and Google Cast receiver. The app is available for Windows, Mac, Android, or Amazon Fire. Since Reflector supports receiving both AirPlay and Google Cast it can receive audio/video from iOS or Android.

It's from Squirrels, the same company that makes the excellent AirParrot app (which allows you send AirPlay audio and video from Windows and Mac to AirPlay and Google Cast).