App to remotely control music on my android phone using another device?

maybe try this:
Remote App Launch

never used it so i can't help with the app, but give it a try. it just needs a browser to remotely launch the music app so you can do this on any other device like your s2.

 

https://play.google.com/store/apps/details?id=com.teamviewer.teamviewer.market.mobile

 

Think you need a player app that can be remotely controlled by another Android device. The only two I know that can do that are Kodi and VLC, both of which have companion remote control apps. Although they're primarily video players, they can do music as well.

 

https://play.google.com/store/apps/details?id=org.atomixproductions.VirtualDJRemote

 

The only app I know which meets your requirements is SoundSeeder.SoundSeeder helps the user to listen to music via multiple devices at once. Hope this will be helpful for you. You can check it on Google Playstore

 

VLC is a good one.

 

I use VLC as well. Works pretty good

 

VLC is pretty great of casting different kinds of gengars (major sp) of all kinds out there.