just found out that with the latest version of MPC video renderer shipped with MPC-BE but you can also install separately and use with other players (ie MPC-HC) you can enable HDR
It eats less CPU than madVR with SVP and I find that the rendering looks quite the same with 4K HDR content.
It is easier to setup also and I had issues with madvr sometimes (which is not really maintained)
If you are using windows 11, set "Auto display HDR on/off" to "not used" : this setting is supposed to switch HDR on windows, but windows 11 does it automatically (as long as you enabled HDR in control panel), picture will be too dark otherwise