Music PI is prepared for this.
I offered a raspberry pi image and an Andorid app.
Burn the image into raspberry pi, Install the app to your phone, and setting the network to use it.
Music Pi support FLAC、MP3、WAV format audio file currently. Before use it, make sure read the FAQ first.
Not like volumio，Music PI can cache audio file into your phone, and play it by phone.
Music PI released under MIT License.