I was wondering if anyone could tell me what the differences between these two headphones are and if its worth the extra money. The a700's are not that much more money and I was wondering if it was worth it.

Hi, I am considering getting either the hd555 or the hd580, I don't know which would be better for my circumstances and was hoping someone could tell me. I am only going to be listening to them on my computer for the most part, I need them because my roommate goes to bed early and I can't use...