Usage Tips:16-600Ω Bluetooth HiFi Headphone Amp: Support 16-600Ω impedance headphone help headphones with high impedance or low sensitivity to be better driven, and can improve the volume and sound quality of headphones. It is delicate, compact, lightweight, and portable that can be carried conveniently. Two-Stage Gain Switch & Bass Boost: It enhances the signal input Into the amp circuit for optimal performance of the headphones.With bass switch, providing more delicate and mellow bass performance, giving you a more shocking music experience. Bluetooth & 3.5mm AUX Input: The upgraded HiFi headphone amplifier not only supports 3.5mm(AUX) audio input, but also supports Bluetooth connect, SNR Greater than 100Db and THD+N 0.02%, make it possible to output a sharper and more real stereo sound without distortion. Easy to Use & Volume Control: Simply connect the AMP to your audio source via 3.5mm cable or Bluetooth, and connect it to headphone, the music will flow to your headphone. It design with battery and volume control button, so you can adjust the volume on the Bluetooth HiFi Headphone Amp. Wide Compltible & Portable: This headphone amp is remarkably compatible with a various of digital devices with 3.5mm AUX output such as MP3, MP4, phones, PS4 controllers, and Type-C input is compatible with Macbook, more mobile phone, computer, notebooks. Material: Aluminum alloy colour: black Package Contents: 1 x Headphone Amplifier 1 x USB Cable 1 x Audio Cable 1 x English User Manual Only the above package content, other products are not included. 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.