... 80 hours (200 hours standby) 2.cost-effective portable headphone amplifier, perfect sound quality A CLOSE LOOK:Technical parameters1 ... output power: 100mW +100 mW2. Headphone Adapter Impedance: 16-400Ω3. recommended headphone impedance: 16-64Ω4. harmonic distortion ... circuit.2.independent professional circuit design, cost-effective portable headphone amplifier, perfect sound quality.3.TI, HIFI level ...