@sns,
other than CPU noise clocking matters at least as much. Depending on the connection chosen you need to either clock the dac in USB asynchronous mode or both dac and server with superior clocking through the same device. Unfortunately all connections between dac and server as well as clock connections have their own jitter/noise issues so that an optimisation only on the cpu is insufficient. Roon in most implementations adds a further device as you need renderer and server, further exacerbating the clocking issue. This is why current design thinking seems to converge to integrated server/dac/attenuator solutions with external power supplies