750$ Intel NUC vs $6000 Aurender N200: I don't hear the difference

We should better understand this as one was better only in terms of subjective sonic preferences and system synergy. The system and owner ears/preferences wanted more full bodied warmth. His comments clearly said this. In audio, nothing is ever universally better. It often comes down to system and room synergy coupled with subjective sonic preferences. I owned the same Roon server and my Innuos Zen was a clear step upwards sonically. Just so much better to my ears in my system. No right or wrong here. Always best to hear a piece in one’s own system to determine for yourself. Glad the OP did this.

In a system with plenty of warmth and body and an owner looking for more speed, detail and resolution, the other server may have been preferred. Welcome to the wonderful world of subjective tastes and all manner of variables inevitably leading to differing conclusions!

The conclusions found in this one instance have absolutely no bearing on what you would determine with the same two units in your system.

Streaming is not hard. Any modern commercial computing device does it well. Dac is where the big sound differences come in.  It’s been this way for years.

Take for example your common Roku streamer that cost less than $100. Does high res video and sound which is way more challenging than streaming say cd res audio alone. Case closed. You will find good sounding audio streamers at most any price point. Just because historically good quality music sources were expensive vendors leverage that to bring modern products to market. But the value proposition of high price streamers alone is highly questionable IMHO.

Do you really believe such bargains exist? I don't think so and neither does anyone else.

Everyone who understands the technology does not think bargains exist, they just think the expensive one is over priced. There is a difference. If I have a $1000 - 1 gallon pail of white paint and a $40 - 1 gallon can of white paint, and no one can tell the difference when they are on the wall, is the $40 can a bargain or the $1000 one over priced. Some just cannot except that one of the tested products is a $1000 can of white paint.

Burn in on a streamer?  What exactly will change w.r.t. what comes out of a streamer after burn in compared to before?

I myself have been hovering around the use of a Streamer Set Up as a Source to work with a Bespoke Built Valve Output DAC I am using.

To see a comparison that is showing that a Streaming Method has the Possibility to be closely compared to a much more expensive device when demonstrated to each other side by side is appealing to myself.

It is certainly enough to encourage myself to consider the method as a starting point and not have to part with the Monies required to acquire a much more expensive Branded Streaming Device. 

In the past I had looked into a NUC as I had seen it referred to as a method and I am sure there was a leaning to the NUC, to be used to supply the music files only and this could be done using the NUC RAM, which was claimed to be much quieter as a method. It is all in the past now and I may be a little bit off course on the method being referred to. 

I am yet to be convinced from my previous experiences of being given demonstrations of Streaming Devices that a Streaming Source is able to deliver in a manner that is on par with a well thought out Vinyl and CD Source.  

How the comments made by other contributors to this thread reflect on how the assessment of the comparisons has been evaluated are beyond my learning stage at present. I am happy to learn more on this if further description is offered. 

Reports like the one from @essrand about their experiences encountered are welcome by myself, and this thread has been a valuable discovery.

{. . . }  does not think bargains exist, they just think the expensive one is over priced. There is a difference.

precisely my thought.  Its true that 'too good to be true' generally isn't rue, but let's be real - what do you think is inside that streamer?  A computer.  Maybe a NUC.  Maybe a Pi.  Maybe something else. A LPS, a nicely isolated SPDIF and USB interface. All well and dandy - bu you are paying a lot for it and the fancy faceplate (generally the fancy package is the single most costly part of any high end component, followed by power supplies).

Now, i do think that you ought to be comparing the price/cost to a NUC, +LPS, +isolation between the NUC and the USB I/F and if possible a separate power supply for the USB.  +Excellent clock if SPDIF is used and in source master mode.  That begins to add up.  But not to $6k

The isolation may well exist at the DAC's input. Not all methods of isolation are created equal - i believe in using a transformer to fully isolate including split grounds.  I have also found, and cannot explain, that even with most "isolated" USB inputs isolating the driving USB from the computer/Pi still makes a small, but real, difference.  My only explanation is that the isolation is good, but imperfect.

I re-iterate that a 3- layer solution with server, bridge and DAC is my preference (Roon core, roon bridge, roon endpoint). It forces more isolation and moves heavy processing away from the audio signal (processing = power draw = power supply and ground noise).

The new Pi4s are leagues ahead of Pi3s in terms of USB bus powering BTW.  Alas they still draw a LOT of power at startup, as do NUCs.  Like 2+ and 4+ amps respectively.  So actually i power the Pi in split mode - noisy side with SMPS and audio side with LPS (~< 0.5A)