I have a NAS with all my music on one of its drives. MB reads from this drive.
My plan is to get a Raspberry Pi plus Hifiberry. The NAS will connect to the RPI, the Hifiberry to the Amplifier.
The whole thing will be controlled through an app on my tablet that will connect to the RPI through WiFi.
It's less then Eur 60 (I have a NAS and a tablet already).
Music Bee 3; EAC; MP3Tag; Music on Synology NAS 115; Logitech Media Server on RPI 3; RPI 2 with Hifiberry; Poweramp for Android/Lineage