With subsonic you should only hear the rifle action and the impact.
I took the suppressor off and shot it without ears once just to compare. The difference is without the suppressor, it rattled my eardrums. With the suppressor, it was just an extremely loud sonic crack farther away from the gun. If you wanna be a sniper without subsonic, you better have a fast getaway vehicle and only need one shot.
I have yet to hear a suppressor that's "movie" quiet.... I've heard dozens, and own a half dozen. And I shoot subsonics in all of them. Most of them sound like a nail gun with a big burst of gas. The closest to "movie" quiet was a bolt action with subsonics. Just a little PSST, and click of action.