I recently found this Flicker image after following a bog on OS X Daily.
Being the curious person I am, I dedided to try it out. It works. I compared it with the normal iTunes presets: “Acoustic”, “Loudness” and “Bass Booster” (my favourite) and this setting still stands out. It gives you high amplitude without cipping the waves; edges are refined beyond measure. Though mine is a bit altered to sound better, this is a very good place to start.