While we never actually speak about ROCK and Nucleus improving fidelity, I would like to make a note here because you used the word “huge”. Before continuing, note that I have nothing to sell you here. ROCK is free and we already have your “Roon money”.
Huge differences are all you can expect when moving from a general purpose “computer” to a Roon OS based “appliance”. Let me explain…
You may get no improvements upon upgrading, but only if everything was configured correctly and your system was set up to run like an appliance anyway. However, we find that most people benefit from the dedicated machine optimized to run Roon well. You’d be surprised and how many people are still letting MacOS mess up their audio streams because they play to “System Output”, or the Spotlight indexer destroys their CPU & IO performance, leading Roon to stall in playback (pops and skips). Even the GPU may be overloaded and the UI could cause the system to freeze during playback.
Many (not all) people do get a huge difference in audio quality, but it is due to a improvement in the digital stream being more reliable, and the settings always being “right”… or you may get zero difference.
It all depends on the situation.