Thats not my experience with MMG's and the 1.6's for over 25 years. They take time to dial them in. But everyone's room and electronics are different.
I didn't say it doesn't take time to dial them in, but it doesn't take much to get them to disappear either. The dialing in part, for me anyways, is getting the imaging, staging width and depth just right as well as getting the right about of "weight" for the phantom center image.