You can use this circuit when your device is connected to a small power amplifier._x000D_ Suitable for audio small signal amplification, 10 times magnification (20db),_x000D_ Can directly drive the headphones (not recommended to be used with the power amplifier output)._x000D_ Power supply: DC 9-19V( it is best to use linear power supply, switching power supply is easy to produce hum)_x000D_ the amplifier chip is dual operational amplifier NE5532, the input and output are 3.5mm ordinary headphone jack and RCA lotus jack._x000D_ _x000D_ Plug Type:EU Plug,it applies to Indonesia, Germany, France, Spain, Italy and so on_x000D_ Voltage: AC 220V_x000D_ Material: Metal_x000D_ colour: Black_x000D_ _x000D_ Package Contents:_x000D_ 1 x Headphone Amplifier_x000D_ 1 x power adapter(Note: Random shape, don't accept the specified shape.)_x000D_ _x000D_ Only the above package content, other products are not included._x000D_ Note: Light reflection 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. _x000D_ _x000D_ _x000D_ _x000D_ _x000D_ _x000D_ _x000D_