Audio PC

I am hoping that there is going to be released an operating system written specifically for a music server PC that offers a suite of tools to make it as good as possible. I am still waiting, it may exist already and I have to discover it.

Yes, there is.  Euphony Stylus, which is more of a Linux operating system that has been pre-tuned to work best in most systems.  It contains it's own music player or you can install Roon Core, HQPlayer, NetworkAudio HQP endpoint, Squeezelite LMS endpoint, or Airplay audio server.

https://euphony-audio.com/euphony-stylus-operating-system/

Alternatively, you can get Arch linux and start digging into all the configuration.  This can ultimately get you better than Euphany, but it requires tons of time and experimentation as well as Linux knowledge.

@rixthetrick - here's a really long thread talking about Euphony and AudioLinux:

https://audiophilestyle.com/forums/topic/55873-shootout-at-the-linux-corral-audiolinux-vs-euphony/

One quote that stood out to me:

" A Euphony Stylus license may seem expensive, but I get such good sound, as well as great support and troubleshooting from Arthur, and the Euphony engineering team makes incremental updates regularly. "

I have not used Euphony Stylus or any of the Linux implementations.  Sorry.  I'm running Windows 10 PC because it's used as a multi-purpose computer, gaming computer and sound system.  I'm running an AMD 5900x based system with a Pink Faun S/PDIF card using AES/EBU as connection type.  Farad Super 3 as linear power supply for the Pink Faun.

Fanless CPU heatsinks are good if you have a relatively low powered processor:

https://www.fullysilentpcs.com/product-category/cpu-coolers/?v=7516fd43adaa

These are actually HUGE heatsinks.  However, they are not good enough if you're running a 12-core CPU for gaming (like me).

I tried Fidelizer a long time ago and it actually did weird things to the audio on my desktop (in other words, it did not improve it).  It did however improve audio from my crappy laptop, so verdict is out.

I have found that running Windows with stock kernal timings seem to be the best.  In some cases, the windows WASAPI drivers sounded better than kernal streaming from JRiver. lol.  If I was doing a dedicated music server, then I would look at Euphony Stylus and doing a closed silent PC with a relatively lower power cpu.  However, I have specific needs for a general use computer that has to server as a miscellanous platform, gaming platform and music playback along with data redundancy for all my personal financial data (quickbooks, etc.).  So I had to pick very specific parts when building this.

So now I focus on how good the sound card is and how good the power supply is.  The Pink Faun S/PDIF with Farad power supply is just excellent!  I will eventually add on their custom OCXO clock, which should give me significant improvements.

NOTE ON PINK FAUN:  There appears to be a compatibility issue if you run Pink Faun card on a Linux platform using Intel CPU (sound breakup problems).  This is a weird problem with the chipset used in the Pink Faun card.  Pink Faun engineers and Linux engineers have worked on this issue for many years but nobody can figure out the root cause.  Intel CPU with Windows appears fine though.  There is no issue with AMD processor and general consensus is AMD actually produces better sound as a digital transport.