iPod owners love their audio players and will do almost anything to customize and improve the iPod experience. Some people are not happy with the maximum volume of the iPod and would like to boost that up to ear shattering levels. Enter the Simpl Acousitcs A1, a headphone amp that clips on the back of the iPod. The A1 is supposed to provide louder output with deeper sound response. A review by the Press Democrat seems to think so too. $149.