Description Innovation Power Supply Design With DAC Decoder USB intelligent Charging By internal NX3 it's a 2400mAh large-capacity litchium polymer battery,charging 0.5hour,it can work 5 hours. 220V working voltage can give full play to the op-amp and guarantee the good performance. NX3 is able to drive high impedance headphones which enough dynamic level range NX-3 can adapt to the charge output of computer USB port and varitey of plugs. It automatically adjust the suitable charging current with the fastest speed to supplement the battery. Specification Weight: 145g Min THD+N:0.0018% S/N:108db(RL=250Ω,GAIN=L) Dimensions: 66mmx108mmx13mm Battery: 2400mAh Rechargeable Frequency Response: 10Hz-100KHz Output Power: 103mW (RL=16Ω,THD+N=1%) 98mW (RL=32Ω,THD+N=1%) 30mW (RL=250Ω,THD+N=1%) Suitable Headphone Impedance: 16-300Ω SoundCard: PCM2704 HI-FI USB DAC SPDIF Package 1*NX3 Headphone 1*Audio Cable 1*USB Cable 1*Silicone Band 1*Velcro 1*Manual