The fear I have with motorcycle audio is that if the motorcycle itself can damage your hearing, turning the radio or whatever up so you can actually hear it will do twice the damage twice as fast. You will eventually get to the age where you throw in the towel and resolve not to get into any more noise than you can avoid...meaning it's either the iPod, or the bike, but not both at the same time. I hope if you have not got to that point you will do it before your hearing is unsalvageable.