Xduoo XP-1 WM8740 High Performance USB DAC Portable Headphone AmplifierFeatures: XP-1 is the first direct digital audio data transfer from Android 4.0 or above cellphone; also, it can be used USB DAC for PC without having to drive. DAC uses two parallel WM8740 It built-in a OP+BUF architecture, high-slew-rate, OCL output capacitor-less with Split power supply. The device improves the sound quality immediately, and let you own Hi-Fi mobile phone Bass boost ON/OFF Switch Adopts the professional DAC chip WM8740 x 2 Rechargeable li-polymer battery with integrated charging system Use aluminum-shielded case to prevent external interference noise One 2-Setting Gain Switch to set GAIN according to the headphonesDirect digital audio data transfer from Android 4.0 or above cellphoneWith PC audio decoding function, using high-performance PCM2706 chip, provides I2S interface for decoding, supports up to 16bit/48KHz digital signalBuilt-in a OP+BUF architecture, OCL output capacitor-less with Split power supply, ultra-low distortion, low noise, high-slew-rate for analog signal Specifications: Power Source: DC 4.2V built-in li-polymer rechargeable battery Output Power: 150mW 32¦¸ load Frequency Range: Audio In:10Hz100KHz ?R0.5dBUSB In: 20Hz20KHz ?R0.5dBGain: +3/+7dBBass Boost ON: +4dB low GAIN, +11 dB high GAINTHD+N: 0.001% 1KHzS/N: 110dBSuitable: Earphone Impedance: 8¦¸?300¦¸Playback Time: >20H DAC input, >30H AUX inputCharge Time: