I am going to buy a pair of headphones for my powerbook and my iPod for when I am on the go. Now, since I like my music sounding as nice as possible, I was considering the Senneiser 650s... but I am kind of worried that they are a little bit too power hungry and won't really sound that good on an ipod. Is there any truth to my worries and how would it be on the powerbook? I just don't feel like spending this much money if it isn't used to it's fullest potential anyways. Thanks for any input.