[Gereral1]

I'm using generic 3DLUT supplied by @Soli convert HDR content to SDR by using external 3DLUT. (bt2020to709-4000to300-0.15blacklevel-0offset)
The other higher nit values crushed the blacks. I entered it in all 3 choices BT.709, DCI-P3, and BT.2020.

Where would I get a 3DLUT so I could try Process HDR content by using 3DLUT? I cannot create one.

Correct, Powerdvd17 doesn't work without the HDR tab switch nor do any other players unless they are post processing (dare I say under assumption) simulated static setting HDR. I also assume native Windows HDR allows reading of metadata and tailors individual scenes vs post processing generic static setting good enough for all scenes but not ideal.

Gereral1 is telling us (again, I assume this what he's conveying) he is playing a UHD HDR from a dedicated player and seeing how the scenes were meant to be seen. He is then playing test files through the PC and comparing the gamut. He is correcting the settings on an individual basis, title by title, to match the dedicated player output by eye. He is then storing the settings in individual .cal files placed next to the title. Upon playback, the settings are sent to the registry making the necessary adjustments to the player controls, and returning to defaults when playback is finished.

Although this method might be considered primitive from the MadVR camp, his individual settings per title are not static and might leave some of us pleasantly surprised? How well independent editing from one author holds up is another story. Just sayin'.....

Gereral1 is telling us (again, I assume this what he's conveying) he is playing a UHD HDR from a dedicated player and seeing how the scenes were meant to be seen. He is then playing test files through the PC and comparing the gamut. He is correcting the settings on an individual basis, title by title, to match the dedicated player output by eye. He is then storing the settings in individual .cal files placed next to the title. Upon playback, the settings are sent to the registry making the necessary adjustments to the player controls, and returning to defaults when playback is finished.

This is exactly what im doing. Believe it or not this matches hdr uhd movie and the pc samples played thru mpchc.
Every movie uses a different level of contrast so your adjustmets will vary per movie Ive tested this on 12 other titles....amazing results.