I haven't looked into playing back Flac files from Mobile devices. I'm currently using a client on the Mac called Audirvana, but intend to use something on the

I haven't looked into playing back Flac files from Mobile devices. I'm currently using a client on the Mac called Audirvana, but intend to use something on the Raspberry Pi like Volumio for general listening, connected to an amp and speakers. The Flac files are just available on the LAN from the NAS. I think Synology does support Plex too, which would let you listen to tracks away from home.