MK 4.23 Clean Boost Pedal - Chrome Unity to +24dB of totally CLEAN boost Power internally stepped up for +28dB headroom to handle the hottest amp effect loops. Flat Frequency and Phase Response from below 20Hz to over 20kHz. Incredible 0.0005% THD+n with less than -115dBu noise floor. That's 140dB+ signal to noise ratio! Can be used as a DI to plug directly into the line input of any sound system