Portable HiFi Stereo Audio Headphone Amplifier 1. Easily fit into the smallest of pockets and works with all your music devices, allowing you to carry it with you anywhere walking, jogging and cycling, or travelling on the bus, train and plane. Now for the first time you can conveniently enjoy Hi-end sound on your smart phone, MP3 player, tablet, laptop or PC. 2. Simply connect the headphone Amp between your headphones and your music player to enjoy great quality sound. It has more than 5 times the output power and half the output impedance of a regular phone, which means the sound wont distort no matter what headphones or volume you use. 3. Portable headphone equalizer is a link between your music player and your headphones. It is a tiny amplifier which can produce the kind of premium quality audio that you expect from hi-end audio equipment used by audiophiles and sound producers. This is the high-fidelity sound provides. 4. It can compatible with headphones, portable speakers, MP3, MP4 ,Mobile Phone, Computer, car stereos, and other audio devices that use 3.5 mm plug connectors. 5. The device is with long standby time, automatically loading detection function, there is no power button. 6. When the headset plugged in, the device will power up then the system automatically boots. 7. When the headset pulled out, the device will automatically shut off. 8. If the internal better voltage is less than 2.5V, the protection of system will automatically shut off the power supply. 9. Frequency: 2-27KHz. 10. Noise ratio: 95DB. 11. Dynamic range: 90DB. 12. Resolution: 70DB. 13. Size: 5.5x2.2x1cm.