The FiiO L7 Dock Kit is designed to be used with the FiiO E7 and FiiO E17 USB DAC/Headphone Amplifiers and provides a dedicated line-out signal from the FiiO E7 and FiiO E17 via a 3.5mmm stereo socket, for sending a high quality line-level signal to other devices such as an amplifier, stereo system or powered speakers for example. The FiiO L7 dock expands the versatility and flexibility of the FiiO E7 and E17 USB DAC/Headphone Amplifiers, allowing it to be used as a dedicated DAC device. The FiiO L7 dock also has a built-in USB jack, allowing the FiiO E7 and the FiiO E17 to be charged and used at the same time.