TOPPING NX2 Ultra Slim Portable Audio Amplifier Quality Promise-NX2s has CE, FCC and RoHs certification and exceeds the requirements of Hi-Res Audio. NX2s uses OP(OPA1652)+BUFLMH6643structure to increase output power to 140mW x2(32)maximum power, suitable for all kinds of headphones. Thinner and Lighter-with the height of 9mm and the weight of 74g, it can be more convenient. USB DAC + Headphone Amplifier- Can be used as PCs external USB DAC. Compatible with Iphone and Ipad with lightning port and Android devices Long Working Time-Built in 1000mAh, provides 40 hours playback time.