Hoi - if I interpret it correctly: You want to be able to play your MP3 or Flac collection (on one or this NAS) on Sonos? If that is what you want YES - you can. Add via service (and select SMB, SMB share on NAS) - I have a pair of Sonos with library linking on a Syno myself (works quite well with older and newer NAS, I've noticed).
If you have any questions: ask ;) LG