Particularly the HFI-580.    I tried looking around and came across some posts that said something about Ultrasone extending their warranty policy to five years, but I couldn't find anything official.   I'd like to know how long the warranty lasts, what repairs I'm entitled to, etc.  ...

So I was looking to purchase a pair of cans from A-T off Amazon and I saw that the company selling it was an authorized dealer, but the order was fulfilled by Amazon.    In this case, is the warranty still valid? 

So I'm looking to buy some closed headphones that are less than $100. I've been doing some research and I've been eyeing these:   Audio-Technica ATH-M30: $50 Sennheiser HD448: $60 Sennheiser HD280: $75   Which of these would be worth buying? I saw that the 448's have had several...