An interesting comment on server sound coming from Raphael Pasche, designer of CH Precision (July 2018)
It is the main reason I ordered an Extreme - I do not want to wait such time to enjoy streaming!
https://www.hifi-advice.com/blog/specials/an-interview-with-raphael-pasche-of-ch-precision/
HFA: Do you know of a reason why Music Servers also differ in sound?
Raphael: I think the collective answer from the entire industry is that we don’t really know. Nobody knows exactly. Think back to when CD was first introduced. Audiophiles agreed that it didn’t sound very good in the beginning, but look how far we came and it’s pretty decent now. I think we will see a similar process for servers and streamers. There are just a few more things that collectively we have to do. We just have to eliminate layer for layer, what is causing the problem, and this takes time. We provide the receiver, the Renderer, and people can do what they like on the source side. We do get a lot of feedback from our customers, which gives us clues.
Interesting that those comments come from a DAC manufacturer that does not build servers. There seems to be a bit of a divide between the "no difference between servers when ethernet is output from the server directly into the DAC" crowd and the "server quality is critical, no matter how it connects to the DAC" crowd.