If your goal is to build high resolution library then I would pick a better server than Mac desktop. You have a nice DAC, pair it with a better server or streamer and keep the door open for streaming options whenever you’re ready.
Vault 2 is a good start up option but certainly not long term. I would look into something like used Aurender N100H which has 2TB storage on board. The Aurender’s conductor app is solid and easy to follow. Use your Mac to download music and then transfer it to N100H internal drive. The files on internal drive will sound slightly better than any external storage on your network.
And lastly, I recommend NativeDSD or ProStudioMasters for DSD and high resolution files over HDTracks. HDTracks are notorious for upscaling lower resolution files and selling them as DSD’s. They have not been transparent about provenance of original file or resolution.