I never had a problem with my iPod Classic sound quality, but since yesterday, there suddenly is an unbearable high-pitched hissing sound in the background. Sound appears generally muffled and low-quality, like a broken cassette tape. I don't consider myself an "audiophile", this isn't a microscopic frequency shift, it's really noticable. First I thought, my headphones were broken but both the standard Apple ones and my trusty Sennheisers produce the same, muffled, hissing sound now. Things I tried so far: - Messing with the Equalizer (it doesn't affect the hissing so I turned it off again) - A "reboot" using the menu+middle button. No change. - 3 different headphones, all the same sound problems. The only thing I did with the iPod, recently, was saving a lot of data files (30+ GB) on it, using it as a temporary harddisk. But I don't see how that would affect sound quality? I didn't drop it, didn't spill water on it, didn't install any hacked OS... Sigh. I don't want to return yet another Apple product. Every single Apple device I bought broke apart after a year or so, despite me treating it like it was made of porcelain. What else is there I can do and is this a common problem? I read a lot of people have it with an iPod Touch? But mine worked before. It is only that way since a day ago!