Can the sound of 'phones deteriorate over the years?
I have a pair of Senn HD480 headphones which I've owned for about ten years. When I bought them I thought they were the bee's knees, but these days they just seem bass-less and shrill. I can't say whether it's happened suddenly or whether it's been a gradual thing, but you know there's something wrong when the Sony earbuds with my kids' £70 MP3 players absolutely waste them at the low end. My once-beloved Senns just seem to sound like someone's rigged-up an high-pass EQ and reduced every frequency below 200Hz by about 10db.
I don't think they're damaged as such, but is it possible they've just simply deteriorated with age and use? Or could it be something else? For example would buying new ear-pads help (these original ones are a bit aged and tatty it has to be said)?