@joel  My source is primarily going to be an iPod Touch or a Macbook Pro, and I have no amp but I'm looking to get a portable. Also, as I said before, I am pretty new so I don't understand your second question.   @Wuss  I will definitely read that guide, seems very helpful thank you so much...

I'm pretty new to the headphone game and I'm looking for a nice pair of over-ear cans.  I currently have a pair of Sennheiser HD 485's, but I'm looking to upgrade to something better.  I'm not necessarily a hardcore audiophile, but I am a musician and I am pretty particular about sound quality...