Recently I've been proposing a two ethernet port solution as optimal for a streaming setup with optical conversion and/or separate server and streamer/end point.
Originally, I used a simple server only setup, using usb out to dac, but over the years my research showed many converting to two computer setups (server/streamer) with great results. At the time I wasn't using a switch so in trying to figure out how I could make this happen I came across this interesting thread, https://audiophilestyle.com/forums/topic/30376-a-novel-way-to-massively-improve-the-sq-of-computer-audio-streaming/#comment-613370
As a result I was able to convert to two computer setup with great results. Since then I've tried any number of devices, both prior to and after server. By far the most effective have been post server, with optical conversion and quality streamer being amongst best overall upgrades.
With the two ethernet port setup one can do away with audiophile switch (the idea of which is quite contentious anyway). Why detour back through an ethernet cable, through the switch, then yet another ethernet cable only to end up in the same place you could with a single ethernet cable with the two ethernet port setup. More possibility for noise to enter chain is never a good thing with streaming.
It seems very few server manufacturers understand the inherent advantages of dual ethernet port setups with exception of Antipodes and Small Green Computer, perhaps others I'm not aware of, please inform if there are. They should at least offer it so people can at least try optimum setup for server/streamer with present server.
Say what you will about server/streamer setups vs. servers alone, but the mere fact you have to go back through the same circuitous route mentioned above to try optical isolation is another demerit for the single ethernet port solution. Optical conversion, in my experience, has been easily one of the best, if not the best streaming upgrade I've experienced. This, and the optimal interface to separate streamer, together make the dual ethernet port solution a deal breaker for servers without.
I can only tell people to try for themselves different streaming setups, there are so many varieties sometimes its hard to keep track of. I can only say the opportunity to optimally interface with optical and/or separate streamers/end points makes dual ethernet port servers inherently superior to servers without.
