There's no easily-accessible means of defeating the protection. If there were, they wouldn't waste time making sure that you can't destroy your hearing by blasting full volume into high-efficiency earbuds and killing most of the cilia in your inner ear. (If you could, they'd be open to lawsuits. Just a warning on the screen has been determined, by many courts, to not be enough. (Most people press OK without reading anything.)
And you WILL ruin your hearing. Not all at once, but as cilia die, your high frequency limit keeps going down, until you get to the point that you hear a constant 4KHz sound in your ears. Even in a soundproof room, with ear muffs that kill all sound, you still hear that whistle. All day, all night, until you die. It's no fun. And hearing aids that actually help when you do that to your ears cost more than the most expensive cellphone on the market. Each. Mine cost US$6,000 for the pair, and that was years ago - the price has probably gone way up since then. (My loss wasn't due to earphones, but to an explosion I was too close to, but half a watt of audio into a pair of earbuds will do the same thing in not too long a time. So will 120 watts into pair of high-efficiency speakers in a car. By the end of this century, "huh?" will have become one of the most used phrases in English.)
