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

I won’t argue with @essrand’s experience. I’ve never used a NUC so I can’t offer an informed opinion.

But it’s important to understand that the N200 is optimized for USB output, with the SPDIF output available only for convenience, in case the need arises.

The N200 doesn’t have the OCXO clock Aurender uses in some of its gear. If it did, it would make no difference for the USB output. USB connections are asynchronous—the timing of the data transfer is controlled by the clock in the DAC, whereas SPDIF (or AES/EBU) signals are controlled by the clock in the source.

Since the N200 doesn’t include such a clock (to make it more affordable than the N20 and other Aurender products), you aren’t getting the best audio it’s capable of if you use its SPDIF out.

The reason for optimizing the N200 for the USB output was mentioned earlier in the thread: native DSD can be transferred only via USB (or I2S). Therefore many DACs, including my Bryston BDA-3, prioritize the USB input.

Aurender says the USB board in the N200 is physically separated and electrically isolated from the noise-generating CPU board.

@essrand ultimately based his evaluation on the N200’s USB output, which is the correct method. So I do not mean to argue with his conclusions. But none of the comments mentioned Aurender’s design decisions, and it’s important to understand the philosophy they utilized in designing the N200.

In response to some other comments/questions in the thread — 

I disagree with the suggestion that it’s better to invest more money in a DAC than in a server. DAC technology has been advancing rapidly for a decade or more now. As a result, a lot of things have been figured out and a relatively inexpensive DAC can perform at a very high level. 

With streamers/servers, we’re only a few years into the learning curve—it’s a product that didn’t even exist until 2009 or thereabouts. A lot of money is still being spent on research and development, and difficult challenges are being addressed by trial and error to identify what works. That drives up costs for manufacturers and those costs are necessarily passed along to the consumer.

I expect 10 or 15 years from now, high quality servers will be much more affordable. But for now, a server will likely cost more than a DAC if the two devices are of comparable quality. 

Second—someone asked what justifies the extra expense of a server/streamer over using a laptop as your audio source. Servers typically cache the audio data before sending it on to the DAC. That is, they read the digital file in advance and store it in RAM or an SSD before sending it to the DAC, which (as far as I understand it) reduces read and timing errors. 

Most servers use RAM and store just a few seconds of information ahead of playback. But Aurender uses a 240 GB SSD to store an entire playlist in advance of playback. This is advantageous (Aurender claims) particularly if some of the songs on the playlist come from internal storage while other songs come from Roon, Qobuz or Tidal. During playback all the songs are handled equivalently since they’re all coming from the SSD cache. 

Aurender has also introduced what they call Critical Listening Mode. When you switch it on, the display switches off, and so do any background processes that are a source of noise. I don’t believe Critical Listening Mode existed when @essrand carried out his evaluation a couple of years ago. Reports are that it makes a significant difference in sound quality. 

I’m not trying to promote Aurender here. I’ve  been researching music servers—I haven’t bought one yet—and I’m using Aurender to illustrate the advantages (theoretical or actual) of using a streamer/server instead of a laptop computer.

I am probably listing my NUC I7 with LPS if anyone is interested. Feel free to PM me. 

I've heard HUGE differences between coaxial and USB on my Aurender N200. Remember this unit doesn't have OCXO like the N20 does and this will impact the performance on the coaxial. The USB sounded way better for me, but my DAC is at its best with its excellent USB interface! If you can't tell a difference between the N200 and an Intel NUC then something is seriously wrong. Also, you should be comparing them using the same interface.

I didn’t read the entire thread but I saw this post and it didn’t stop me from trying the N200. The test conducted by the OP is flawed in several ways. 
1. As already mentioned above the N200 is optimized for USB. The spdif out sounds fine but it’s very audible how much better the USB is. (see the posts above talking about the N200 clock)

2. Tidal sound significantly worse than Qobuz with the N200, and I think with Aurender in general.

So for the comparison the N200 was set up in a worst possible way. But even in this configuration I would expect it to beat the nuc. I tried streaming with my mac mini and it doesn’t hold a candle yo the n200.