1, Hi-Fi Power Amplifier 2, 42W 3, Frequency: 15Hz-50KHz 4, Warranty: 3 years FEATURESHI-66 headphone amplifier have reliable quality, best tone. SPECIFICATION ModelHI ... <0.8%S/N92dBOutput3GroupsInput1GroupPower Dissipation42WFrequency15Hz-50KHzSize6N6x2pcs;12AX7 X1pcGrow Weight440x240x300mm9.5kgs Naphon : Headphone Amplifier HI-66