Kanto Headphone Amp Audio Component Amplifier,Black (YARO2-AMP) Optical (Toslink) Audio input, 3.5mm stereo mini-jack aux input, USB DAC Audio input, subwoofer output, 3.5mm stereo mini-jack Injection mold ABS construction 4 ohms nominal impedance, class D amplifier, 140W peak power (70 watts total RMS) 450 mV input sensitivity, &lt; 0.1% total Harmonic distortion, 20 Hz - 20 kHz frequency response AC 100V - 240V 50/60 Hz Universal power supply, &lt; 0.5 W standby power consumption