Topping NX1A Digital HiFi Earphone Amp Portable Headphone Amplifier Type: Portable Headphone Amplifier Spec: designed for MP3/MP4/mobile phone/computer that can not get best effect of high impedance from the headset due to the low power. Frequency: 20-20KHz-+0.2db SNR: 105DB Dimensions & Weight: Net Weight:93g .Size:About 9*5.8*1.35cm Labor: 1 year