Yes, that would be the best option but it is really hard to tell for me which drivers are "best" ones without any tests and in many cases I don’t think I have required knowledge to judge if the driver works right as the differences between versions could be very subtle in details I do not know about… 
For me - latest versions should have most bugs fices from previous versions so that’s why I’m looking for them - I know, it is not a perfect reason, but at least it is "something".
I didn’t know about that optimisation - thank you for pointing that out. That version is indeed on Realtek website.
As I said, I was thinking it is the same case as Intel - Intel does not offer latest drivers on website but the latest drivers have higher version number and they are better.
As I said, I didn’t know about this specific optimization - I was thinking that they are offered for all OSes.
As I mentioned, I’ve checked MSI website for different X99 board (but still on Windows 7) and MSI offers newer driver than Realtek website for my OS so that’s why I thought "newer drivers" are for all OSes, not just for Windows 10.
It is stupid to search for the latest drivers, if the previously released drivers are better.
As I said, I didn’t know that that these older Realtek drivers are better - nobody told me that until this time.
I am aware of that, but still it’d be good to have "the most possible up-to-date drivers".
Anyway - that conclusion "Realtek HD Audio driver v6.0.1.8186 is probably the best one for my needs" is very important for me and ends my searches for now - thank you very much.