I put sound deadening material on both hat cymbals, but not the bells. Real cymbals are concave and don’t touch except at the very edge so you have no worries about things getting pinched or squished. Normally you install the jack in the bottom bell, or drill a hole to fish the wires. So you’re all set in that regard. I’ve actually squeezed my 25k slider into the inside of the hat as well, plenty of room in there for all sorts of goodies. 😉