If there is one lesson to be learned from this and the story on the thread it's never ever use headphones with any exposed metal in them, plastic all over is the order of the day.
I would not trust the plastic to be insulated to 300V either, I would suggest not using headphones when the device is plugged into the charger, and get some external speakers instead. Used PC amplified speakers are cheap, or free if you look around a little. not going to be anything close to Hi Fi, but then again with low bitrate mp3..............