Features: 1.Name:Headphone Amplifier 2.Model:AMP-i4 3.4-channel stereo headphone amplifier for all types of headphones 4.4 independent volume control knobs 5.Best sound quality can be obtained even in a high volume levels 6.Each channel has output level 7.Ultra low-noise 4580 operational amplifiers ensure superior tone 8.High-quality components and exceptionally rugged construction ensure long life 6.Mini portable headphone amplifier system for studio and stage applications Specification: 1.Color: Blue 2.Input interface: stereo 3.5mm TRS interface, stereo RCA interface 3.Input impedance: 22k ohms 4.Maximum input signal level: + 22dB 5.Output interface: stereo 1/4 "TRS interface, stereo 3.5mm TRS interface 6.Output impedance: min 16 ohms 7.Maximum gain: 19dB / Channel 8.Signal to noise ratio:> 98dB 9.Power supply: AC 12V, external power adapter 10.Size: 113 * 73 * 40mm 11.Power cable length:Approx 1.5m Package included: 1 x Headphone Amplifier (Audio cable are not included) 1 x US Power Adapter (A free adapter will be send according to your country)