Manufacturer's product description:
The smallest portable headphone amplifier in the world!
Improves the sound quality for MP3 MP4 Players Computers or Mobile Phones when using earphones or headphones.
Save your player battery and lengthen the play time when playing music.
It’s not about volume but Quality. A great pair of headphones can change you're listening experience--but only if they are driven well and properly powered. Put an E3 Headphone Amplifier between your music source and your favourite pair of headphones or earphones for an awesome personal listening experience right between your ears.
Designed for high impendence and low sensitivity headphones, with bass boost function;
Small and easy to carry and use in the outdoors;
Increase your music player's play time;
Uses only one AAA battery, for 20 hours playtime.
Output Power 70 mW (32 ohms Loaded)
12 mW (300 ohms Loaded)
Signal to Noise Ratio >= 90 dB (A Weight)
Distortion < 0.05% (10 mW)
Frequency Response 10 Hz - 40 kHz
Suitable Headphone Impedance 16 ohms - 300 ohms
Weight 11 grams (without battery)
Power Supply 1 AAA Battery
Dimensions 55 mm x 23 mm x 14.5 mm
Dimensions: 2.17 in x 0.91 in x 0.57 in
Weight: 1.52 oz