Going over the functions, adjust the Ratio of original sound and overdrive. Guitarists can mix the clean and drive correspondent via the clean knob. Second function, by the Attack knob, players can adjust the width and the thickness of the timbre, this practical function is also useful for metal music. Under Jazz and Rock modes, you can get distortion and viscosity in different degrees. Big Rumble is equipped with the same clean boost with HOLY AURA, providing 20db of high gain. This Clean boost is so good, that Tone City decided to use it in the Big Rumble model as well to provide EVEN MORE possibilities of timbre. Specifications Input Impendence: 1Mohms Output Impendence: 10Kohms Normal input level: -10dB Engine A turn on only: 11dB Engine B turn on only: 10dB By pass: True by pass Current Draw: both engine turn on 25mA Power Supply: DC 9V regulated Product Dimension: 12 (L)*10(W)*5.2(H)cm Product Net Weight: 0.35kg