Precautions while using Earphones
Excessive noise in Headphones
If children will be using portable audio equipment you try to stop them! then responsible parents will want a safety method that limits noise exposure without constant supervision. Protection in the form of powered adapter using signal processing to significantly enhance the users listening comfort is a safe method but requires batteries to work. Modern headphones are usually very sensitive as they have to work with battery powered mp3 players and similar devices. So when you plug them into a mains operated unit they can usually produce very high sound levels.