Pyle Home PHE3AW Headphone Amplifier with Bass Boost (White) (Discontinued by Manufacturer) Designed for high impendence and low sensitivity headphones, with bass boost function - Signal to Noise Ratio: =90 dB (A Weight) - Dimensions: 55x23x14.5(mm) Small and easy to carry and use in the outdoors - Distortion: 0.05% (10 mW) - Weight: 11g Increase your music player's play time - Frequency Response: 10 Hz - 40 kHz Uses only one AAA battery, for 20 hours playtime - Suitable Headphone Impedance: 16 ohms - 300 ohms Output Power: 70 mW (32 ohms Loaded), 12 mW (300 ohms Loaded) - Power Supply: 1pcs AAA size battery