The DAC is galvanically isolated from the PC, and on that matter I would dare state that the PC can not make a difference.
So, WiFi, seperate videocard, overclocking are also allowed in the dedicated audio PC.
So no more power tweaking and such (CPU, RAM)
Wow, dedicated audio PC, is no longer a necessity, just get a fast PC.
No, or better ni.
1) Wi-Fi contaminates the AIR and all electronics are subject to the dangerous RFI and EMI. We cannot do a sh*t, but shield every piece of equipment very well.
Why? Because unless you live in an isolated, very isolated villa, you'll have already a few wi-fi networks hanging on you. Try with any modem or smartphone. My iphone picks up an average of 2-4 from my neighbors.
So the recommendation of Peter to avoid it only apply if you dont have it already. Otherwise, I dont see other solution than shield every piece of electronic gear in a thick mu-metal cage.
2) Non dedicated PC - I think Peter answered you on this. Various processes can still influence xxhe, that is the sound, so best to avoid. But the computer can be fast, as long as fanless and EMI/RFI controlled (note that Peter has his computer FAR from the DAC and his system, AFAI Remember).
3) PC PSU. Here instead special care to the computer power source ***should*** NOT be needed anymore, when using the NOS1, with its special interface.
But, what is needed is a filter to block the noise FROM the PC psu and any other switching equipment that is connected to the same power line (I mean line not plug) to protect the OTHER electronics in picking it up, namely the amplifiers (the NOS1 seem to have an excellent PSRR by itself)
I'm going to build such filter for about 300W power, single rail and 6 plugs. It'll be open source/diy.
At this regard if someone can source the fabric used by Furutech to absorb EMI/RFI, it would be a nice addition.