My TT came with a 8 strand SBD string and I liked the release and how it shot. So I decided to try one on my 56" 54.5@29 BW PCH. Turned into a bit of a learn experience, which is good. Anything that is worth while is.
    It sounded like a bass when I shot it. So I gave Pierre Lucas at SBD call. He said the PCH has tended to be a little loud. He had me send him the string back and replaced the cat whiskers for yarn puffs. That really did not help much. So he asked me to raise my brace height and try heavier arrows. I took it to almost 9"(BW says 8 to 8.5). Made a lot of difference. I thought it would really affect the spine, which would affect the flight of my arrows...it did not. Pierre said he has one person shooting a PCH at 9.5 brace. Mine is shootable for hunting now.
    Is there anyone else that has ran into this and can you tell me how you handled it and what your bow setup is?
   Moreover how about that service from Pierre. Never charged me to replace the silencers. He wants the SBD strings he puts out to perform. Thank Pierre

I shoot mine at 8" and it is pretty quite.  Using  10 strand D97 string, its 60 lbs and shooting a 590 grain arrow.  Use the wool yarn puffs.

I shot both of mine at 9 inches.

I be it's still not near as quiet as the TT. Mine sounds like a long bow going off.

Put some Bow Hush on the string at each end. Really muffles the bowslap.

Have you tried Astro Flight sting yet?  I just made up some 12 strand strings with it and its is super soft and quiet.  PM if you want some details!

I found the same thing on mine. My SBD string is at about 9" brace on my 56" pch and its much better.

I have a PCH with two sets of limbs....wasn't loud at all from the factory....but I made it even quieter with Bow Hush and Hush Puppies.

Looking forward to shooting a deer with it REAL SOON!