Recommended Server?

OK, if not downloading music what features do you want? I use the Zidoo Z10 Pro as a media server and it works great:

https://www.zidoo.tv/Product/index/model/Z10+PRO/target/7ogeLPHKQt1KKmVViAFMcQ%3D%3D.html

If you are not downloading music, how will you be using the server? Only as storage for ripped CDs? Or as a streamer for a music service such as Tidal or Qobuz, etc? Or both?

As a streamer only for a music server.

Aurrender. I own two after experimenting with others for years (you can see them in my virtual systems). The higher level one you buy the better the sound quality. Aurrender only makes streamers and they are among the best, if not the best at various levels. 
 

I only listen to Qobuz… although I store my old ripped files on it for the very infrequent internet interruption. 

As a streamer only I would recommend the Martin Logan Unison. It has ARC room correction which works great and is on sale at 50% off:

https://www.martinlogan.com/en/product/unison

Review:

https://www.techhive.com/article/582813/martinlogan-unison-review-dts-play-fi-and-airplay-preamp-streams-anything.html