Those enhancements are provided by the sound card manufacturer and not Windows itself.
I wondered about that (and have seen some similiar answers to postings), however upon inspecting the driver in Windows Device Manager, it now shows it as 'High Definition Audio Device' and the manufacturer as 'Microsoft.' I believe it showed up as Realtek before, but don't hold me to that...
As mentioned earlier, I only had the option to use Realtek's manual room calibration while its drivers were installed. Now that I've gotten rid of them, it has reverted back to the windows drivers and I now have the automatic DRC available (and works wonderfully, I might add).
Don't know why I had such a time getting rid of the realtek drivers, but I'm quite happy now!