2017.06 Model X, noticed Dolby option is replaced with new immersive sound, I thought this is only for MCU2 cars, tried to switch between off, standard and high, no changes at all on the sound, and then did a reset, Dolby option came back. But few days later, immersive sound setting is there again. The only thing I can tell is when immersive sound setting is there, the volume of the music is noticeable lower than the Dolby at the same volume level.