I know it is possible, Daniel. I once attended a class put on by Rod Jenkins who had just received and set up a new Black Widow recurve bow he was shooting 3U. As you probably know, Black Widows are not known for being particularly quiet, but this bow was quieter than any bow I’ve ever heard except for some compounds. Rod was going to use it for tournament shooting, so I’m sure the arrows were not particularly heavy. One factor may be that Rod knew what tiller he wanted, and had Black Widow make the bow that tiller, which was not their normal 3U tiller.
Personally, once I set the nock point to get a slightly nock-high arrow flight, there’s not much more I can do about the mechanics of a non-ILF bow to get it quiet. The two main sources of noise I work on are limb slap and limb bolt vibration. I think that’s why longbows are usually quieter than recurves: they don’t have limb slap and they are usually one-piece. Some people go further and move the silencers around until they get the least sound from the string, but I just set ‘um and forget ‘um.