If you have selected the Realtek sound device directly as the output device in Audio Settings, and check the option for Open Device For Exclusive Access, then MC then will talk to the sound device directly and bypass the Realtek's control panel mixer, thefore the Realtek's EQ settings will be ignored and you can use the settings in MC.
Yes, exactly this. In WASAPI Exclusive Mode, the effects in the driver should be bypassed and can be safely ignored (or used for non-MC audio, if preferred).
If you want to verify this, you can just apply some crazy-obvious effect (like one of the "dank tunnel" echo effects they always include) and test. I believe that some device drivers can still apply effects even in WASAPI Exclusive mode (if it is done "in the driver" after the Windows APIs are done with it). Perhaps ASUS sound cards or something? I don't think this applies to any modern Realtek onboard audio, and I could be totally off base. In any case, if such a thing is possible, there should be an option on the Advanced tab of the device's Properties dialog (where the "allow exclusive" and "give exclusive priority" options are) that says something like "allow driver effects in Exclusive mode".
Or something like that. I'm pretty sure I've seen such an option, and read about devices that do this, but I can't find it on any of my computers and a brief Google search turned up nothing.
So, perhaps I'm crazy, perhaps not. Either way, check that Advanced tab and if there is such an option, uncheck it.