Feature: 1. LOW NOISE: 4 channel volume amplifier adjustment kit for headphone or speakers, each channel output has a separate volume key, minimum distortion at the highest sound, non crackling, with ultra low noise, excellent sound quality 2. QUALITY TONE: The 4 channel headphone amplifier makes each signal carefully amplified, and modifies the sound quality and tone on the basis of increasing the output power, providing quality sound enjoyment 3. CONTROL WITHOUT INTERFERENCE: Each channel of headphone amplifier has a volume control knob, which can fine amplify each signal, and do not interfere with each other 4. WIDE APPLICATION: One in four out stereo headphone amplifier, bring quality analysis, fluent listening, can be used for all types of headphone 5. SUPERIOR SOUND: The headphone mixer amp features an ultra low noise 4580 operational amplifier to ensure a superior sound, you can use with confidence Specification: Item Type: 4 Channel Headphone Amplifier Line Input: Type: 1/4 inch TS connector, stereo Impedance: 100kΩ Maximum Input Level: +15dBu Headphone Output: Type: 1/4 inch TRS connector, stereo Impedance: Approx. 80Ω Maximum Output Level: Approx. 40 mW in 100Ω External Power Supply: 12V 150mA Size: Approx. 47 x 57 x 104mm / 1.85 x 2.24 x 4.09in. Package List: 1 x Headphone Amplifier 1 x Supply Adapter