PRO D1 is a passive DI box: It has an unbalanced input interface, which is a 1/4-inch (6.35mm) interface, for connecting musical instruments or other unbalanced signal sources, such as electric guitars, electric basses, keyboards, etc.; and a balanced output interface, which is an XLR interface, for connecting to a mixer, audio interface or other equipment that requires balanced signal input. The input and output are equipped with isolation transformers to isolate ground loop current infection, and also have a 1/4-inch Thru interface to send unprocessed signals to other devices, such as amplifiers on stage, for live monitoring. Frequency response: 20Hz - 20kHz, which can ensure the integrity of the audio signal and enable good transmission of both 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): Used to reduce the level of the input signal to prevent signal overload. The attenuation values are 0dB, -20dB -40dB. Ground Lift: Used to disconnect the Pin1 transmission on the DI box XLR jack to prevent current from flowing along the shield between the DI and the microphone preamplifier, thereby disconnecting the ground loop and eliminating noise such as hum caused by grounding problems. Applications For acoustic guitars and bass guitars Connect consumer audio products with professional audio equipment Eliminate "squeaks" and "hums" caused by ground loops Outstanding features Ultra-rugged design for extended service life Plug and play, easy to operate Completely passive design, no power supply required Colour:As Shown Material:Metal Tips: The product may be updated constantly ,Due To Different Batches, Th