I have a Mac Mni and I hate it for audio. It kept crashing for a few years when updates were applied. The solution was to re-install the OS and then the updates. Though the Mini did not crash like this last year. Maybe Apple learned something.
During the last 2 days I switched between a $500 Dell low-end tiny computer running ROON Core and my $6000 Silent PC (client bought for me) that also ran ROON Core. The sound differences were 0.
Silent PC | Fanless PCs and Quiet Servers
The reason being that I ran fibre optical cable just before the DAC. I used a couple of Sonore Optical Rendu’s for 2 systems. I am back to the $500 computer. They reason for the computer switching was related to some issues I had with PowerLine data transfer that was unrelated to the computer audio processing. The reason I got the SIlent PC is that I use it in my office with 6 monitors and to do that with a regular computer would result in a noisy computer.
If you dig into the ROON web site of Community Forum, ROON themselves suggest using a cheap computer and sticking into a closet and then stream from that source. They do not mention fibre like I am recommending but the glass cable of a fibre setup cannot carry network analog noise into the DAC. ROON maybe not saying that today with the new owners and the need to sell the new ROON server machine.
A computer, especially a noisy one like the Dell Precision (I have a few), that is directly connected to the DAC via USB is sending the analog noise of the computer into the DAC. A RJ45 network connection is also able to carry noise, but likely not as bad as a direct USB connection.
Saying all of this I do have a PlayBack Designs Streamer-IF and that also supports USB directly from a computer. I do not use it like that, but I think there is some magical processing going on inside that unit because it sounds great on SPDIF even without any fibre in the pathway.