DAC connection to computer

Travelinjack-I agree with you but some of the other posters are way off base. 
My server running Roon will never be hooked up to a dac. When I was using this Mac straight into the dac, the server was in another room and I used Ethernet to the dac.

All the Auralic/aurender server/streamers are computers, no ifs and buts about it. They run a proprietary version of some hacked Linux OS, big deal. I’ve done this before running Linux on a commercial server with commercial solid state technology (again using Ethernet to the dac) and there was no benefit to sound quality. IMO, the only benefit you will see is if the server/streamer claims they have an audio usb port, which some drool over. Me, I’ll never use it. You can buy thousands of $$$ of usb gimmicks/tweaks and it will still be flawed.

Who cares if a new Mac is running another task in the background. The new Mx processors run 38 trillion ops, so I don’t think it will slow down any. But, I turn off everything that is not needed during my listening sssions, after that I run my backups, etc.

You take a Nucleus that the vendor removed all diagnostic commands from the OS thinking that it will improve the sound. If it was running on 30 year old gear, that would be the right thinking, but not running anything in the past 10 years. Now nobody can figure out what is wrong with their nucleus, they can only guess which usually leads them to buying new hardware which might not be the problem.

I stream Qobuz from my ASUS Windows 7 computer to my DAC via USB. I have also ripped my CD collection (<4000) to uncompressed FLAC and I use Foobar 2000 to play those files. I kept all my CDs and play them regularly.

I have compared Qobuz playback to the corresponding CD (Jay's Audio CD3 MK III transport) and I can't hear the difference. I have also compared my ripped files to the physical CD and same result - no difference.

If the computer is doing something horrible to the sound it's beyond my ability to hear it. I suggest that you try comparing the CD to the streaming service you are using, assuming that it provides CD quality, and see if you can tell them apart. Just make sure you have carefully matched the levels.

Having said all that I am going to get a dedicated streamer one of these days but it's due to convenience instead of sound quality. I'm looking at an Eversolo DMP-A8 which will allow me to use a phone or tablet to control playing the content.

For whatever reason my experience is that digital sources don't have the range of sound quality of other components. I have 3 DACs, two transports, one vintage CD player, and a SACD player. I've compared them all and they sound very similar, if not identical. I realize that lots of people on this forum hear enormous, life changing differences, between streamers, internet switches, and digital cables ("The XYZ BLEW AWAY the ABC") but apparently I have tin ears. But those ears have saved me a ton of money.

@8th-note I am right with you on the not hearing any significant difference between my computer to the DAC and a much higher cost individual streamer/more expensive DAC combo. 

I read some posts on this site about the use of a DDC.  So I bought a DDC (Denafrips Iris) which I tried which was a greatly lower cost tweak. I believe (can't be sure because I can't AB test it like I did computer/old DAC vs. expensive DAC/separate Streamer) I am hearing some significant differences such as clearer more pronounced bass and some detail without the digital glare in the upper range. My belief is enough to feel that the sub $500 cost was worth it. 

@8th-note You can use a phone or tablet to control foobar2000 in your existing setup. This thread has a few suggestions.

USB. No one yet explained any physical concepts of "bad sounding" PC. You can use reclock/DDC if you are really concerned with "noise" coming from the PC.