PRO D2 is a passive DI box: it has 2 unbalanced input interfaces, which are 1/4 inch (6.35mm) interfaces, for connecting musical instruments or other unbalanced signal sources, such as electric guitars, electric basses, keyboards, etc.; there are also 2 balanced output interfaces, which are XLR interfaces, for connecting mixers, audio interfaces or other devices that require balanced signal input. The input and output are equipped with isolation transformers to isolate the ground loop current infection. It also has a 1/4 inch Thru interface, which can send unprocessed signals to other devices, such as amplifiers on the stage, for live monitoring. Ground Lift: Used to disconnect the Pin1 transmission on the DI box XLR jack, preventing current from flowing along the shield between the DI and the microphone preamplifier, thereby breaking the ground loop and eliminating noise such as hum caused by grounding problems. Frequency response: 20Hz - 20kHz, which can ensure the integrity of the audio signal and enable good transmission of high and low frequency signals. Input and output impedance: The input impedance is 50kΩ, and the output impedance is 600Ω, which helps to reduce signal reflection and distortion and ensure effective signal transmission;Attenuation (Pad): It is used to reduce the level of the input signal to prevent signal overload. The attenuation values are 0dB, -20dB -40dB. Model: PRO D2 Colour:Black Material:ABS Package Contents: 1 * PRO D2 Audio Isolator