With the Electro-Harmonix HEADPHONE AMP, you can rock out anywhere without disturbing your neighbours. Simply use a 9V battery and any pair of headphones you like, as long as they have an 3.5 mm plug attached to them. The go anywhere HEADPHONE AMP delivers a musical quality and attitude that defines the spirit of Electro-Harmonix. As uniquely musical as it is portable, the ultra-light Headphone Amp let’s you practice as loud or funky as you want without waking up your street.