I personally had the issue for the steam version of the game. Resinstalled the game and windows 10 OS almost a dozen times, nothing. Updated and installed latest drivers and bios, nothing.
The game simply refused to launch in dx11 ( as soon as the green button was pushed the process just ended without an error message ). I did have realtek R audio but I didn't have any steelseries headset or anything else.

Here is how I solved it:
I went into the steam directory directly to find the `ffxiv_dx11.exe` instead of going through the regular boot.exe.
Upon logging in with those, error messages finally showed up, the issue for me lied with two `system32` dll files. `MF.dll` and `WMVCore.dll`

I downloaded them from dll-files`.`com and replaced them within the system 32 directory. With win10 it forced me to replace the `trustedInstaller` default permissions.

Hopefully it helps some people to figure out how to debug your own.