You can do this in Spotify, it's actually one of the main reasons I use it. You need to add your local directory to the list of music sources. The trick to gett

You can do this in Spotify, it's actually one of the main reasons I use it. You need to add your local directory to the list of music sources. The trick to getting that music to sync to other devices is that you need to create a playlist and download it while both devices are on the same local network. Your personal library is never uploaded to the cloud.