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

In terms of your problem logging in to Qobuz, your firewall may be blocking their site. I’ve had this problem and had to have Netgear tech support unblock it in my Nighthawk Wifi 6 router. My thoughts are that with a tube based DAC you probably won’t hear the difference between the lower noise floor of the N200 over your NUC, especially while using ROON because the tube noise is above the noise floor of the least capable source, namely the Intel NUC. I recently moved from a similar setup, got rid of ROON which has it’s own SQ issues and am now using a high quality streamer/server made by NOVATRON that has built in storage and runs on a linux custom processor and has exceptionally low noise characteristics, a highly accurate clock plus exceptional physical build quality with much attention to detail, yet only costs about $2K . This allows my (slightly) below premium grade Gustard X16 SS DAC (connected by USB)  to really strut it’s stuff. One would not have guessed a streamer/server could make that much difference but it really does. 

OP, do not be led to believe there is anything wrong with your hearing or impressions. You are not the first to report hearing zero difference between servers. I suspect many owners of high cost "audiophile" servers will denounce such a finding as nonsense.

I have long been skeptical of high-end servers. Some claim to use custom motherboards, but most use off-the-shelf processors from AMD and Intel. Their proprietary operating systems are touted, but most are based off Linux. I also see a lack of accommodation for upsampling, which requires a lot of processing power. Most servers are simply not powerful enough to do upsampling, at least beyond DSD128. Support for software like HQPlayer is also lacking.

If one is willing to do DIY approach, a SOTA server can be built for fractions of the cost. Take a Mac Mini or Intel NUC, boot it from Audiolinux (which has native support for Roon and HQPlayer), add a LPS, and connect it to your network with ethernet.

I took my Intel NUC, which has a custom analog power supply to RMAF one year. The Aurender was used at the show, but the system was set up using my NUC. Aurender lost big time, but it really had no chance. I use my NUC in an engineering and a recording system besides using it as a streamer for my personal stereo.

So, the real answer to what is better lies in the answer to the question "what software are you using". My answer, "the good stuff". This includes the driver for streaming ie USB driver software. I do not use the "free stuff". What's the difference, the clocking and the data stream accuracy.

I put these software packages on my engineering laptop, gamers would like it. It performs almost as good as my NUC as a streamer and will definite give commercial streamers a run for the money.

I have been using computers in my engineering, recording, and playback systems for years (Kleinbeck Engineering), 40 years to be exact. That was before IBM sold their first "PC's" and Sony made the first CD player. It makes analysis of the results much easier and much more reliable because I calibrate my systems to a known standards.

However, simplicity does have its rewards. Not a computer nerd, maybe commercial streamer is a better choice for you.

@jrapp Qobuz works with my NUC running Roon but not Aurender, so it's a Aurender problem.

The basic conclusion I am taking from all of this is that there isn't a very big difference between an Intel NUC and a dedicated music server. It is approximately equal to upgrading an USB cable, if that.

Better to spend money on upgrading cables, DACs, Amps, etc etc, than spending 1000s on a music server.

There was a review on Computer Audiophile on the Grimm Music server MU1 where the reviewer (THE reviewer) says he heard no difference in USB outputs of the 10000 euro Grimm server and his NUC.

So while I agree, better USB/clock etc in a dedicated server might make a difference, it is not a lot and certainly the price/performance upgrade ratio seems low. 

Crux of the story: I bought a lifetime licence of Roon and sticking to Intel NUC for the time being and keeping the $12000 (price of Aurender N20) for future upgrade on cables or a Shindo preamp :)