After deciding on the Audio-Technica ATH-A900Xs as my headphones of choice, I then realized that my mp3 player (currently a well-used iPod Nano 6th Generation) might need an amp.  So then I went looking for one and found the FiiO E6 portable amp.  Do I really need an amp for this setup, or would...

Alright as my first post here (I've been lurking on and off for a year or two) and since my headphones left channel audio decided to quit on me, I'm wondering about the major differences between these two Audio-Technicas.  Since my musical tastes include just about everything and these...