in physics that doesn't work ^^, it can only make the force more efficient and that would depend on the persons foot arch and stuff. I had a Sansa fuze, but I recently returned it. I only say that the iphone boosts the mid range, compared to my on board sound card. Either way I want a slightly more dark sounding amp that will hopefully give me a little emphasis on something rather than sibilance. I mean really all I'm asking is what will help the sibilance, I know the amp is not the main factor in sibilance, but it certainly makes a difference.
making the force you apply more efficient > higher vertical jump > it does physically work
the shoe forces your foot to be in that particular arch, therefore enhancing your jump