Unless you have drivers on Windows that requires you to use Windows, ROCK will be a better experience, and most likely sound better on the same hardware as well.
W2012 is trim, and Audiophile Optimizer trims it more (and adds enough to make it audio server capable). AO takes a large operating system and trims it with no support from Microsoft. It’s a tough project, and it’s amazing it gets where it does. But ROCK in a different class. It starts with nothing and builds up. Every piece is custom built from scratch, even the cross compilers. Everything is trimmed to be the bare minimum and focuses on one task: the best RoonServer experience. Just as matter of comparison, the core operating system services of ROCK consume only a few dozen megabytes – the larger than the black box of just the Windows kernel.
I speak a bit to the optimizations in this post: