This much wrapping will definitely compromise the sound of the instrument, as it was designed to enhance sound vibrations as much as possible. And as far as marching band goes, unless your fingers and hands generate a large amount of heat that can be transfered by touching the valve keys, this won't make the euphonium "warmer" because the thing itself is not generating heat. And how do you wash the instrument if it's wearing clothes? HOWEVER, that's one stylish euphonium!