So far I have ruined the headphone jack of one iPhone and one iPod with the the trauma from the frequent yanking of the heavy cable of my Sennheiser HD280 Pro headphones:
I think the damage mostly happens when I keep the iPhone or iPod in my pocket and walk around. Not only will my leg push the plug, but the heavy cord will also yank it slightly with every step. Because the plug is much larger than that of Apple's ear bugs, it becomes a larger lever, gradually loosening the jack.
Apart from getting lighter headphones, how can I prevent it from happening again? The best idea I have come up with is to use a six-inch extension cable with a right-angle plug; this should at least reduce the leverage.
Will this be sufficient to prevent damage? Does anyone have better ideas?