Dumb question, but if you're worried about the safety of plugging your headphones directly into a dodgy receptacle, why not just buy a couple of adapters for under $2? A 3.5mm stereo female to (2) 3.5mm stereo male cable ( http://www.monoprice.com/Product?c_i...seq=1&format=2 ) will run you $1.38, and a 3.5mm stereo female to 3.5mm stereo male cable ( http://www.monoprice.com/Product?c_i...seq=1&format=2 ) will cost all of $1.65.

If prior users have left the unit in an unhealthy state, you really ought to invest in prophylactics.