The Earthworks ZDT 1021 is a high quality 1 channel Mic/Line preamplifier. It delivers a frequency response of 1 Hz to 200 kHz at +0.5 dB, a rise time of 0.27 microseconds and distortion of less than a millionth (0.0001%), making it so accurate that it is barely noticeable. With the ZDT 1021, signals are transmitted absolutely crystal clear and distortion-free.