In 1.9, you can choose the source of the played sound via the /playsound command.
(cf : http://minecraft.gamepedia.com/Commands#playsound)
It would be nice to be able to choose the source when playing a sound from a plugin, for custom music plugins for example. So the player will be able to correctly manage his sound settings.

It's currently possible using performCommand() but it's not very neat.

Thank you