1. It would be highly recommended that the music files be moved from the vault to a Nas or somewhere that has redundant storage.
2. My NAS runs the basic UPnP server to index and manage the music- the metadata, tags, annum art, etc.
then my Lumin (a D2) streams the music, and the App does the controlling
I’ve seen some people that don’t like the app, but once learned, it’s good.
All Lumin hardware use the app
The U2 mini looks like ice kit.