That solves an issue I've had as well, though it shows the MacBook Pro isn't really the fault. I have a Samsung TV (no ground-pin) and I would often watch it while using my MacBook Pro plugged in (ground pin). Because I didn't have wireless headphones yet I'd run a cable from the Samsung's headphone socket and plug my Bose headphones into that. If I was touching the MacBook case with one hand and grazed the metal parts of the 3.5" audio cable, I'd get quite a strong tingling & that almost becomes painful. Hadn't considered that the fault was the TV's lack of grounding.