Fiio E7 portable headphone amplifier with USB audio decoder (DAC). This product is designed to replace PC onboard soundcard that do not have enough output power for higher-end headphone. With USB audio decoding, amplification and audio output, E7 can serve as both a professional headphone amplifier as well as an external USB soundcard. Main Features USB audio decoding and output for PC, functioning as a high quality external USB soundcard Texas Instruments¡ PCM2706 serves as USB receiver. For better sound quality, a Wolfson WM8740 serves as digital-to-analog convertor (DAC), pairing with a high performance operational amplifier from ADI for the DAC circuit; Build-in headphone amplifier utilizing AD8692 and Texas Instruments¡ TPA6130A as pre- and power-amp for high performance, good resolution, low distortion, and powerful output; Standard 3.5mm stereo line-in jack for portable amplification with conventional audio source; Dual 3.5mm headphone output jack. Convenient design makes it easy to share music between two listeners; Worlds first portable headphone amplifier with dual colors OLED display; Easy to use digital volume control function with great precision and channel balance; Build-in EQ for 3 levels of Bass Boost; Build-in rechargeable 1050 mAH Li-ion battery for 80 hours of continuous operation Specialized dock for connecting E9 to experience an even higher performance Quality anodized aluminum satin finish case design, small and compact, ideal to be wrapped together with digital audio player; User selectable USB charging function to help prolong battery lifespan and lower distortion from power supply circuit; User definable startup volume memory and maximum volume limiter to protect user from hearing damage due to loud volume; Automatic keylock feature; User definable sleep timer function and total runtime display. * This model supports driverless plug and play on Windows XP, Windows 2000, Vista, Windows 7, and various Mac OS. Full battery charge via computer USB port after 200 minutes and capable of 80 hours of continuous operation, tested under laboratory condition for evaluative purpose only. E9 is a desktop amplifier with greater output, better performance and an integrated E7 specified dock connector. With the dock, E7 can easily establish a line-out connection with E9 and transform both together into a high performance desktop amp with USB decoding function, capable of PC connection and recharging functions, etc. Total system runtime will accumulate from the first use. It will be reset to zero after either reset button is pressed, reloading default setting, or when the battery depleted Specification: Output Power: 150mW (16¦¸); 16mW (300¦¸) Headphone Impedance Range: 16 ¦¸ ~ 300 ¦¸ Signal to Noise Ratio: 95dB (A weighted) on line-in; 100dB (A weighted) on USB-in Distortion: 0.009% (10mW)on line-in; 0.008% (10mW) on USB-in Frequency Range: 10Hz ~ 1000KHz Power Supply: Internal 1050mAH rechargeable Li-ion battery Recharging: USB 5V DC 400mA Size: 96mm x 55mm x 15.5mm Weight: 100g Note: Due to the USB spec restriction on digital audio format. This device only support up to 48kHz / 16bits USB decoding function.