I thought I'd post a quick thank you to everyone involved with this project - after struggling to get a very similar project to connect to my NAS I found RuneAudio - I downloaded and installed it on my Raspberry and it just worked! I set up a connection to my OpenMediaVault NAS and there was my library of Flac music waiting to play.
For info I'm using a Beresford Caiman DAC, connected to the Raspberry via USB - and playing through a Rega Mira amplifier and B&W 601 speakers the sound is great. Now I've learned how to do bit-perfect rips (via EAC) the sound is comparable to my Rega Planet CD player!
Thanks again!