The moment of insertion is magical. That first moan has vulnerability, amazement and conquered taboos all wrapped up in a pretty package of sound. It's breathy and soft and surprised and dripping with desire. Especially when it's a bit of a stretch to accommodate what is being inserted.
I had the good fortune to experience that recently. (He chose the biggest one.) And it is the thing that sent me over the edge last night, remembering the sounds he made.
I get such a feeling of power and satisfaction and, let's be honest, a real thrill in thrusting into a man and hearing him moan, repeatedly. Damn that makes me wet.