Go get two or four $3 piezos, hook one or two up to your main amp speaker wire with that capacitor, crossed over at 10000Hz, lay them on top of your speakers and see how they sound. like 'em or hate 'em, it's only $12 to experiment with, much cheaper than your open baffle. Move up the ladder from there if you don't like them. From what I understand, it's only harmonics up that high anyway.