Features: This machine is equipped with isolated boost power supply, ensuring the puritys of signal and wide dynamic ranges. Since it isolated power supply, it can also be used in vehicles without worrying about common ground interferences. Signal processing circuit adopts the ti ne5532 operational amplifiers, which is of high fidelitys (hifi) with low noise. It have left and right channel balance adjustment, volumes control, and three-band equalization adjustment for high, middle and low frequencies. Mute circuit, no impact sound during startup and shutdown Specifications: Component:Metal Size:Approx.128.5x83x34mm/5.06x3.27x1.34inch Power supply: DC5V Power consumption: 0.5W Input and output interfaces: phono plugs Frequency response: 20HZ - 20KHZ Amplification:12db Equalization adjustment ranges: ±15db Input impedance: 50KΩ Output impedance: 600Ω Functions of knobs and interfaces: BALANCE: Adjusts the volumes balance between the left and right channel. VOLUMEs: Adjusts the volumes level. LOW, Middle, HIGH is respectively for adjusting bass, midrange and trebles. IN:Stereo audios input. OUT:Stereo audios output. DC5V:Power supply interfaces, mobile phone charging head, computer USB interfaces, car charging, power supply, etc. can be used. Note: Please allow 1mm errors due to manual measurement. Due to the differences between different monitors, the picture may not reflect the actual item color. Package includes: 1pc Stereo Audios Premplifier This machine is equipped with isolated boost power supply, ensuring the puritys of signal and wide dynamic ranges. Since it isolated power supply, it can also be used in vehicles without worrying about common ground interferences. Signal processing circuit adopts the ti ne5532 operational amplifiers, which is of high fidelitys (hifi) with low noise. It have left and right channel balance adjustment, volumes control, and three-band equalization adjustment for high, middle and low frequencies. Mute circuit, no impact sound during startup and shutdown