The original headphones that comes with the iPod is nothing to shout about. Sure it looks neat with your iPod, but you might as well get a better aftermarket headphone.

Visit the "audiophiles" section of this forum for more advice.

As for warranty, I really really doubt it. After all, it is not a manufacturing defect.

ps : if you don't want to spend extra, just use the headphones that you have with your PSP.