title: Turn Android phone into Bluetooth headset
body: <p>Let's assume we have a rooted Android OS on a device that supports Bluetooth. Can we build an app that advertises itself as a Bluetooth speaker via Bluetooth A2DP? </p>
  
  <p>If that was possible, then any other device could pair / connect to our Bluetooth server app and stream any music / sound. This server app could then take the music stream and play it locally or even send it to other devices via Wi-Fi. This would theoretically enable a multi-room Bluetooth solution.</p>
  
  <p>Any idea how to achieve this? Where would I start?</p>