Features Model AMP i44 channel stereo headphone amplifier for all types of headphones4 independent volume control knobsBest sound quality can be obtained even in a high volume levelsEach channel has output levelUltra low noise 4580 operational amplifiers ensure superior toneHigh quality components and exceptionally rugged construction ensure long lifeMini portable headphone amplifier system for studio and stage applications Specifications Input interface stereo 3 5mm TRS interface stereo RCA interfaceInput impedance 22k ohmsMaximum input signal level 22dBOutput interface stereo 1 4 TRS interface stereo 3 5mm TRS interfaceOutput impedance min 16 ohmsMaximum gain 19dB ChannelSignal to noise ratio 98dBPower supply AC 12V external power adapterSize 113 x 73 x 40mmPower cable length Approx 1 5mPackage Included 1 x Headphone Amplifier Audio cable are not included 1 x US Power Adapter 1 x Plug Adapter depending on your shipping country