The amplifier dynamics is about 100 times, the capacitor is about 22 times, and the music part is about 5 times. The mixed output can drive the earphones. Note that the input voltage * magnification signal cannot be higher than the supply voltage. Please choose your power supply voltage reasonably. The higher the voltage, the bigger the signal. It is not easy to cut out. If the signal is not very large, it can work even if the voltage is lower. Please use a high-quality low-ripple power supply, since the power supply is not good enough to easily produce . The power interface is DC5.5 * 2.1, inside + outside - does not include the power supply. Colour: black Material: plastic Package Contents: 1 * MA-2S Audio Preamplifier Only the above package content, other products are not included. Note: Light and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.