However, the Auralic server easily bested the MiND server built into the Sim unit.
It seems the term "server" is being misused here.
What
@mgrif104 compared was two different software player/renderers and how they handle a buffered audio stream, from a server somewhere else. The Sim Audio does not have a server, nor do the Auralic products. The above statement is simply not true.
In an attempt to clarify for the OP - the term "server" refers to the computing device that the file you are streaming originates from, as well as the software component necessary for the hardware to provide the file to an endpoint using some such or another protocol.
The reasons servers can vary in terms of sound quality can be due to many different things, however in a nutshell the less processing/manipulation of the data happening in the server's software-based component typically has the largest impact.
In other words, your question is about the affect the "server" has on the SQ, not the player or endpoint, and so the differences between the two should be clarified.