you'll need to experiment a bit, but for the most part, most folks are getting quieter bows with skinnier strings. sometimes there's a perception of more speed and flatter trajectories - i get that, too, but for longer distances (35 and up) where i will rarely take a shot at big game.
i use 8 strands of dyneema on a 55# longbow, and some folks go down to 6 strands.
with modern hmpe fibers, most strands are at least 100# in true tensile strength, some are closer to 120# per strand.
i use the very safe formula of 12 times a bow's holding weight. so, for a 55# bow that equals 660#, or a string with enuf strands to hold that much weight.
8 strands of dyneema'02 equals at least 800# tensile strength. lots to spare. life is good. my bow and i are happy campers. :D