I haven't had much problem getting my CH quieted down. There is a slight hum from the big curves after the shot. I don't feel it, but if I pay attention I can hear it. I film a couple shots of myself everyday just to check my form and I can't pick up any of that hum from 5-10 feet away on the video. Put the camera next to the target at 25 yards and I can barely hear the bow go off.
Once I got my nocking point figured out it drastically reduced it. They seem to be fairly sensitive to hand pressure. They like a high grip with the standard tiller). Push those big hooks way out of tiller and you may have more vibration.
These bows definitely store a ton of power. I'm shooting pretty much the same arrows I did out of my last bow, which was 12# heavier in draw weight with the exact same point on. I didn't get a covert hunter to shoot faster, I went with one, b/c I could drastically drop draw weight and still shoot a heavier arrow. I'm sure that helps reduce the sound at the shot.
Here's my specs just so you can compare
-68" covert hunter
-21" riser
-xl hex 7.5 limbs
-52@31
-6 7/8" brace
-3/4" nocking point (3 under)
-4 everlast leeches
-1" strip of velcro right where the string leaves the limbs at brace height
-black eagle x-impact (250 spine, 32", uncut)
-100 grain outserts (the 400 spine black eagle instict outserts fit the 250 spine x-impacts)
-250 grain points
-4x3" parabolic feathers
-13gpp
-28% foc
none of this is needed to have a deadly set-up. But I love tinkering with stuff.