How the string is made makes as much (maybe more) difference than the material. Dynaflight '97 is 100% Dyneema (SK75). So is Fury (SK90). I've been able to quieten tons of bows, including Black Widows, with Dynaflight strings...although for me blended materials (450+, 452X, BCY-X, X-99) have always been a tad quieter before tuning, silencers, etc. I think the Vectran just naturally dampens vibration better.
The best "recipe" for me with Dynaflight has been 12 strands with loops padded to 18 (Flemish). With BCY-X, 18-20 strands with the loops padded to 24 (Flemish). 8125, 14-16 strands with the loops padded to 20 (Flemish). I've never found a "skinny" string to be inherently quieter. Tinkered with them off and on for nearly 20 years on selfbows, longbows, and recurves.
Several variables to consider getting a bow quiet. Nock fit is one that's often overlooked...a nock that snaps on hard is naturally going to make more noise. Your release is another. A good release is quieter, and might be harder to get a good clean release on a shorter bow. Silencer placement can make a difference...you don't just slap them on in any old spot. Normally one at the 1/4 point and one at the 1/3 point on the string is a good starting point, but for the best results you may have to do some tinkering. I once had a bow where less than a 1" difference in silencer placement made a night and day difference. I tie mine on around the string. They won't move on their own, but can be moved up or down for fine tuning. Brace height of course...sometimes a 1/2" can make a big difference. Arrow weight...heavier arrows are quieter. If you use "cat whiskers", don't leave them too long...too long and they will make their own slapping noise.
I start with a "naked" string...eliminate as many variables as possible. Find the brace height that is most quiet (make sure your nocks fit properly, nock set is correct, arrow spine is correct, etc.) There will be a "sweet spot". Might not be a whisper, but you will find a spot that has the least noise and vibration with no silencers. Then add silencers. Move them up or down 1/2" at a time. Might want to keep notes to keep from putting them in the same spots. Some bows might not follow the "rules". I had a fellow bring a bow to my shop one day, he just couldn't get it quiet. We shot and tinkered and shot and tinkered...I was getting frustrated and came in the shop to take a break. He stayed outside and kept shooting. In a few minutes he came in saying "I FOUND IT!". On a whim he'd moved both silencers to about 6" from each end...night and day difference. Weren't supposed to work that well there, but they did.
There are rarely any "magic bullets". Usually there's a solution to a problem, but it takes time and patience.