I'm experiencing the same problem. I just put a FF string on my recurve and have been tweaking mine. So far, I've put new felt pads on the limbs tips, adjusted the brace height, added another set of string silencers and sanded my arrow knocks down more than normal.
What I found was the felt pad material I was using was thinner than what I've used the past. A lot of the extra niose was still coming from the string slap. I amade the change and found a significant difference. I will start to remove some of the other remedies as I don't like a lot of "junk" on my bow and hopefully it will stay quiet.