Headphone amplifier, a slightly improved version of the powerful FiiO E12 Mont Blanc amp. The device delivers 11 clean volts of output power and can drive your high-end planar headphones with aplomb on 'High Gain' or your in-ear headphones equally well employing the A5's sensitive 'Low Gain' setting. The FiiO A5 headphone amp charges via USB connection from any 5 Volt supply via a laptop computer, tablet or most smartphones and takes about 3 hours to fully charge up. The battery run time of the FiiO A5 unit rates somewhere around 12-13 hours. The A5 unit also has a bass boost button, so it does allows for some audio customization for your particular headphones and listening tastes. The FiiO A5's slick and sturdy aluminum build quality joined with its miniaturized but super-potent headphone amp circuit delivers a massive audio statement in sound quality performance and muscular output power from a tiny device. Frequency response of the amplifier rates between 10 Hz and 90KHz. The dimensions of the device are 124 x 65.5 x 14.5 mm and the weight 168 g.