Ujjdwiurgh Audio Amplifier Portable Headphone Earphone Amplifier 16-150 Ohm 3.5mm Jack HiFi Aux for Mobile Phone Music Player

It is not recommended to use while charging, line noise may be generated. This is why the product is powered by lithium batteries, and battery power supply can avoid line noise No, the USB interface of this product only has the charging function Please connect the input devices, like computers, mobile phones, to in port, and then plug the headphones into out port Correctly . Increase the volume of the input device and increase the master volume of the product When an unshielded signal line is empty, an interference signal enter the amplifier and be amplified. If you dislike the sound, we suggest you replace the shielded signal line or unplug the signal line