Marius Masalar takes a look at Doppler 2, a music app that’s built for people that maintain a collection of purchased tracks. The app looks slick and I’d love to give it a try, but you essentially have to transfer your music manually with iTunes file transfer, the Files app, or the app’s built-in WiFi transfer feature.
I currently store my music in my Plex library and use Prism for playback. Prism let’s me authenticate with my Plex credentials and either stream audio right from my server or download the tracks to play them locally. I can pick and choose which tracks to download or, from the library view, I can download all tracks that I haven’t yet. I would love to see Doppler fern this as an option as well. Until then, I’ll stick with Prism.