Description: Upgraded sound quality: top sound quality, let time prove everything, make sound transparent, awaken music inspiration, the new design concept, more than imagination, three-partition isolation circuit, master power, two operational amplifier sets (OPA2604AP+OPA2107AP), treble/bass is felt to significantly upgrade one level after multi-operational serially connecting to the product, which is benefited from the internal ±7.5V high voltage for greatly enhancing the thrust. Details reproduction: The product can capture more details which are not the extra addition to product but the existing ones, because non-professional headphone amplifier often disposes such details. Increased sound field: Anyone who doesn ’t use a good headphone amplifier may never better understand “sound field ”, it is a sense of presence, the sense of scene heard from a transductive headphone is different from that added to the product, it is worth noting that a good headphone amplifier deserves a good headset. Backup cellphone power: The unique product design (cellphone charging) can be used as the backup power. Specification: Audio I/O: 3.5mm stereo jack Battery charging port: Micro USB interface Charging current: 1A Lithium battery capacity: 2100mAH Battery life: ?5-6 hours Internal operating voltage: ±7.5V SNR>100dB THD+N: 0.0003% Output power (thrust): 120mW Applicable headphone (ear bud) impedance: 16-300? Charging interface: Standard USB Charging output current: 1A Package Includes: 1 Piece A935 Headphone Amplifier 1 Piece 3.5 (plug) to 3.5 (plug) audio cable (length: 135mm) 1 Piece Micro USB charging cable (length: 200mm)