If you go with Roon, I would just stick with Airplay for everything. The Roon Airplay features are first rate and probably the best on the market, other than maybe Airfoil. For the NAS route, many of them use their own software. Synology, for example, has Airplay built into most of their NAS if you use their DS Audio app. Of course, apps like Filebrowser can simply access hard drives plugged into your router and you can Airplay from the app using an iPhone or iPad.Good idea Rex. I will do this in the other rooms not having the Vault. Since the Vault has the advantage of the built in cd ripper and storage it is a dream for that. Other areas just streaming Tidal I will try your suggestion.
I am still leaning toward Roon because I have a lot of albums to store.
The main downside to Airplay is it plays everything at 16/44.1 resolution no matter what it is fed. It is bit perfect with that bit rate, though.