Music Server vs PC confused

My answer is no. I have been saying NO to this so much that people must think I am a Sonore xxxRendu fan-boy (a Ethernet-2-USB converter or digital converter). They do work, even with a cheapo, busy, noisy computer in any room of your home, as long as it is connected to your network.

Look at at some of my past posts on this if you want to hear my propaganda on this issue.

Do you use ROON? The Rendu's are ROON READY.

I have not compared the two, but the usual argument for a purpose-built server is that a PC is running all kinds of functions you don’t need and is a very electronically noisy environment. All this noise pollutes your music signal resulting in lower sound quality. A music server is built to only deliver a more pristine music signal. YMMV

If you are using this as purely a "music server" only, then I think the differences will not be that great.  That means the computer can act as the sever (or file server), but you will need a DLNA Renderer/Player devices that accepts the streamed music data and clocks the data to generate the S/PDIF or USB pulses for DAC.

In your case, I think you'll be using it as both a Server and a Player, since you are connecting a DAC directly to this.  If you use a computer, many people have had good results with the JCAT USB card or other custom audio USB cards (think Paul Pang).  You will likely want to get the best power supply (linear power supply if possible).

With a stand alone music server, some of them have fully linear power supplies and good clocks for generating the timing on the pulses (for different bitrates and sampling rates).  The linear power supply makes a significant difference in the digital transport. 

If the mini PC is optimized to be used as a server, not needed functions turned off, and is fanless or doesn't  make enough noise for you to notice then I doubt you would hear much of a difference. 

Good advise from @tomcy6 and @auxinput.

If you’re not opposed to buying used, look for Aurender N100H on used market around $1500. Before stepping up to N10, I spent some time with N100 and it is one of the best sounding server under $3K. In addition to superlative SQ, the setup simplicity and app experience far outweighs any pc setup, IMHO.

Many of us here who have upgraded to dedicated audio server would never go back to mini pc or green computer based setup.