What are some signs that your headphone is about to give up? My headphone suddenly got quieter than before, and voices are mushed together without any clear separation. There is no "attack" with certain sonds (harpsichord, trumpet etc...) as there used to be.

My Ipod headphones started getting quieter but it's been a month and they still haven't given up, but as I recall with previous headphones a tell tale sign they're going to break is a cracking sound while your listening to music.

If they don't sound how you want them to, then they have "given up", and it's time to get new ones. It's likely that headphones much better than what you had before can be bought for pretty cheap.