DEVIALET now Roon Ready.

[BatEars]

1. What do you mean by "the quality of the Roon Core"?  The Roon Core is a software application. It's quality is the same regardless of what it runs on. The computer it's running on can affect things, for example if you're going to use a lot of Roon's DSP functions you need a computer that's fast enough and has enough memory to do the DSP processing or you'll run into problems but you could run Roon on the same computer and have no problems at all provided you didn't perform any DSP functions. There are other things which can affect sound quality, for example I hear differences between output from Roon to my 140 depending on whether I use USB or ethernet, and whether I use RAAT or AIR when I use ethernet but that's got nothing to do with the Roon Core and everything to do with the output choices I make. What are you trying to ask here?

Is there a difference between say an NUC with i7 chip, a PC with same i7 chip running Linux, a PC with same i7 chip running Windows to run as Roon Rock (sorry, got my terminology wrong!   , newbie here)?   Assume they have same ram, disk storage and doing the same thing with a mid sized library, no DSP, no upsampling.   Is the sound quality affected by using a slightly difference platform?  Will adding a linear power supply to the hardware improve sound quality?

What you run Roon Core on (Linux, Windows, ROCK, MacOS) will have less impact than the quality of the hardware and the method of connection.

A fan-less solution will most likely have more impact than a linear power supply will. 

Connecting directly to your DAC endpoint using high quality screened cables will have more impact.

Upsampling to your DACs 'native' sample rate will have more impact.

All of these things will bring marginal gains.

The quality of your DAC, amp, speakers etc will have far more impact.

The beauty of running Roon ROCK on a NUC is that you know it is doing nothing other than running Roon. With other OS options the OS is doing all kinds of things in addition to running Roon and therefore needs more care and attention. ROCK needs virtually none. Whether it sound 'better' is not really the main point.

Once you get beyond basics sound quality is a completely subjective experience. There is no right or wrong. If you find something that works for you, go with it.