Why are you keep trying to complicate things? For the music library (assuming you’ll put the core on the internal M.2) internal vs. external doesn’t make to much of a difference (performance wise) assuming that you are using at least an USB 3, but having the storage split in two will make it hard to manage (and don’t say RAID0 again please ).
You should keep things really simple:
For the NUC way:
- get the best one that you can afford from the roon recommended list.
- ugrade to the maximum (affordable and hardware possible) memory, this will generally improve the performance of any computer system.
- put the core on a M.2 internal, and the music on a SSD internal.
- enjoy the music.
- don’t forget about the back-up, both core and music, on a NAS or on a direct attached (USB) disk.
- safely enjoy the music (even more now that you have a backup too)
For the NAS way:
- go the NUC way (see above);
- use the NAS for backup (2 x 4TB HDD in RAID1 will do);
And, if you really want to complicate things (but in a more elegant way) keep in mind that files in a music library are 100% static (you add files, but you don’t modify them, well, assuming that you are not using Audirvana Studio), so one neat thig that you can do is to treat the music files backup in reverse: your main music files storage should be the NAS, from which you’ll update the NUC when you add new files, and not the other way. This way what you’ll have on the NUC it’s just an active copy of your library and whatever happens there (files corruption, accidental and/or drunk related modification, ransomware, stuff like that) won’t transfer to your main storage. And this also will give you a nice and clean dbPoweramp flow: rip/tag on your computer, move (or copy) to the main storage (NAS), copy to the active (playable) library (NUC). From here the sky is the limit (literally if you want to also keep a backup in the cloud!)