I tried this out for myself yesterday with a fresh install of Windows 10 on both my Control and Audio PCs. The sound with Windows 10 is good ... Very good in fact although the sound quality with Windows Server 2012 R2 is superior in just about all respects. Dynamics and separation are better and stereo imaging has greater focus. I am currently in the process of going back to Windows Server 2012 R2!
Apart from cost, I have discovered another downside to Windows Server 2012. With a fresh install of the OS, it steadfastly refuses to download updates, hanging either when searching for updates or downloading updates. Sometimes the update process would come back to life but on other occasions it was necessary to restart Windows Update and even then, there was no guarantee of success. I googled this problem and it is obviously a known and common issue. In spite of this, Microsoft have refused to address it.
My comparative listening tests lead me to the conclusion that Windows Server 2012 R2 provides the best sound quality. I am however, surprised that Microsoft have allowed this long standing update issue to go unaddressed. Those wanting to install Windows Server 2012 might be advised to look on the Internet for an activation workaround. It is a matter for the individual's conscience but I would advise that by taking this route, you will be paying what the OS is worth and Microsoft will be paying for their lack of good customer service!
Acer Windows Server 2016 (x64) Laptop (Intel i5/8GB) (Audio PC) / Lenovo Windows Server 2016 (Intel i3/4GB) (Control PC) / Audiophile Optimizer 2.20 (GUI Mode on both PCs) / JPlay Femto / JPLAY Femto Streamer / Process Lasso Server Pro / Fidelizer Pro 8.2 / M2Tech Hiface Evo, Paul Hynes Power Supply / Naim Audio DAC with DSD Firmware Update / Naim Audio XPS, Linn Sondek LP12 / Naim Audio ARO / Linn Troika / Naim Audio Armageddon, Naim Audio CDS2 / Naim Audio XPS, Naim Audio NAT02, Naim Audio NAC52 / Naim Audio Supercap, Naim Audio SBLs