The decision for a QNAP NAS should be good. But you should consider what the NAS should do for you!
If you choose a NAS with an AMD CPU some UPnP-Server wouldn’t work
If you choose a NAS with an Intel CPU you are free and could install all solutions there are on the market.
Especially the server solutions from illustrate (Asset UPnP) and Roon (Server) require a Intel CPU or work much more faster with this.
By using an extra UPnP Server on your NAS and not only a network share, you are able to generate your personal look and feel inside your music archive.
For me the Lightning DS app is the one of the best on the market, but yet there are some ‚bugs‘ (I will describe in another new post) which could make difficult to browse and use a large archive. Then an extra UPnP Server could be a solution. At this point: it’s very comfortable that Auralic let the user choose this option to use ‚an external‘ UPnP Server or to use the built in functions from the Lightning DS App.
The AMD solution is cheaper than the Intel solution.
I use a QNAP TS-EC1080 Pro (not only for the music) and came from a QNAP SS-439 Pro. I think the Intel one would give you more possibilities.