Since we took receipt of ROCKI we have been playing around with what does and doesn't work. One bonus is that +Sony Xperia Walkman app on Xperia phones also works well using "Throw"
Open your Walkman app and select the throw icon in the top right and select your ROCKI, then have fun firing your music to your speakers. If you need the walkman app then you can find "versions" of the apk on various internet sources, so use those at your own risk, and of course the copyright / legal issues that follow.