Feature:1. SUPPORT ALL HEADPHONES TYPES: 4 channel stereo headphone amplifier for all types of headphones, 4 high power stereo amplifiers for best sound quality even at maximum volume2. REALIZE MONITOR DISTRIBUTION: Each channel has an output level, so if you're tracking multiple musicians at once, or if every member of the group wants to hear the playback, you'll need a monitor distribution system3. DRIVE 4 INDEPENDENT VOLUMES: The compact, flexible HA400 can drive up to 4 pairs of headphones and up to 4 independent volumes4. OUTPUT LEVEL CONTROL VOLUME: You can use this ultra compact stereo headphone amplifier with any of 4 headphones at the same time. Four listeners in the studio can listen to the main mix while recording, and each listener can adjust their own volume using a dedicated output level control5. ULTRA LOW NOISE, HIGHEST SOUND QUALITY: The HA400 contains 4 high power stereo amplifiers to maintain the highest sound quality at maximum volume. The ultra low noise 4580 op amp offers outstanding audio performance, the same as the op amp found on full size audio equipment, and a DC 12V adapter is also availableSpecification:Item Type: Headphone AmplifierMaterial: MetalColour: BlackProduct Type: 1/4in TS connector, stereoInput Impedance: 100KMaximum Input Level: +15dBuOutput Impedance: About 80Maximum Output Level: About 40mW in 100Product Power Supply: External power supply, 12V/150mA 50/60Hz (US Plug 100-240VAC).Package List:1 x Amplifier1 x Power Adapter1 x User Manual