Can you tell us more about your usage? Do you change headphones a lot? Do you pause the audio before doing so?
Sure, that happened always while music is playing. First two devices came in standby mode from where I was unable to switch them on back again, last one first came into standby, hour or two later it started to turn on again but this time with only left channel and EX750, which were used to test that device this time, were ruined while I performed this procedure. For all three devices headphones was always plugged in and there were no changes till failure.
I'm was aware of possible issues with devices and because of that I did played music using devices continuously till failure of the devices, and as I've already mentioned it didn't took that long, less then 100 hours for every device.
I've also did the same with D30 and A10 - no issues for 200 hours.