Dedicated NUC/Nucleaus vs shared PC (w Fiber Media Converter connected to Endpoint)

I've tried both, a dedicated fan less PC and a normal PC. I could not hear any difference. Even if a music player is the only running app, Windows still runs a plethora of background tasks. I would not worry about that. Besides, any 'dedicated' streamer or player that runs on an operating system does too.

I used a USB to USB galvanic isolator and that made a huge difference. It takes out literally all the PC noise. There also are USB to optical (toslink) converters on the market, 192kHz / 24 bit ... more than enough for normal music playback.

I have both a dedicated music server (the sonicTransporter i9) and a Mac Mini in my HiFi system. When I started with Roon, I ran the Core on the Mac Mini. Since buying the sTi9, I've been running Roon Core on it and using the Mini for DSP software (HQ Player, BACCH4Mac) and music library management. Lately I've been running both Roon Core and HQP on the sTi9.

IMO, concerns about fan and electrical noise from a multi-purpose computer probably are over-blown (at least for relatively new equipment).  I've never tried fibre optical connections, but am a little skeptical about significant SQ improvements. If you turn off background processes (such as Time Machine on a Mac), you can minimize the number of system events that might impact your music listening.  But then, you probably can't eliminate them completely.  That, and the faster processor in the sTi9, are the reasons I use the latter for Roon Core and HQ Player software.  I still use the Mini to download digital music files (from HD Tracks or Qobuz) and expose its music library over the network to Roon and to the file player on my Matrix Element X (streamer+DAC+preamp).

If I were starting from scratch, I'd consider a faster M1 Mac Mini for all the functions currently spread over my 2 devices (sTi9 and Intel Mac Mini).  A Nuc would work, too, but I happen to be tied into the Apple ecosystem with other devices. I probably would not seriously consider a Nucleus because IMO there are alternatives that offer more bang for the buck (faster processors, more software applications, lower cost).

Just my two cents here. A streamer at the end of the day is just a stripped down pc. Yes I understand the concept that by taking out all the other duties that a normal pc does can remove all the issues. Think sometime people are getting into an area of noise and jitter that our human ears are incapable of hearing. In the end is not a streamer also introducing issues as a component in the chain. The argument that if the router as first entry point loosing data that can never be recovered will drive you nuts. If that is the argument then you need to trace your inbound all the way back to you internet provider and ALL it in counters before your house. If it sounds great to your ears just sit back and enjoy the music!

@sgreg1 You can only control what you can control. Just as the electrical grid is not something I can control, so is ISP. Doesn't mean I can't realize full potential of what is offered via equipment upgrades within the home or audio system.

For those who believe a general service computer delivers sound quality on par with dedicated streaming components I'd suggest  doing direct comparisons in home. Both noise and jitter in digital components are easily heard. Contemporary digital far superior to early digital, due largely to massive efforts in reducing both. We are not at end game in these efforts, further reductions now has digital playing at or near level playing field with the best of best vinyl rigs. Lowering of noise floors and reducing jitter to ever more vanishing levels is totally responsible for providing digital with more analog like sound qualities.

For some, general service computers may be sufficient, but to state no better sound quality possible is total nonsense.