.22 subsonic is very quiet. CCI Quiet through the newest top performing cans sounds about like a misfire. Centerfire rifle calibers are a totally different animal, though. Even subsonic pistol calibers with a good can isn’t really hearing safe. Combined with good hearing protection, however, you can get enough decibel reduction to really protect your hearing, though.

Transferring it to the 9mm DOE as per my initial post.

You don't need to wear the gloves you use to touch the can to move it to shoot? I'm lost. Shoot, put on welding gloves move can, take off welding gloves, shoot. Note moving cans that are hot will or may result in removing the flash hider or the hub mount depending on the rotation directions involved and what you used to mount them.