Pretty sure gin's question is "Did you get it?" instead of "Did you hear it". Moreover, for those who look at the movement of his palms, they look as if he takes a praying stance, not as if he claps like people usually do (as appaludes). Then, there is the speed of his palms which are shown to move very fast. If all you want is sound, what is the point in moving extremely fast. He could have merely clapped normally.
And yeah, few would benefit from senjumaru scaling, but squad 0 members(ichibē excluded) aren't that far above captain class. Yamamoto and shinigami aizen are literally considered to scale to them, urahara also scales around that lvl, same for other guys, such as shunsui. This way, this "few" would extend to dozens of people
