what does the frequency shift do to the sound?
It shifts the Mids. With the toggle down, it shifts the tone to low mids. With the toggle up, it shifts the tone to High mids. The up position is kind of like a TubeScreamer, with out loosing the low end. The boost/beast switch boost the gain and the attack. If the boost mode is off, it has a dry tone. With the boost mode on, it becomes more wet or saturated. You can use the assault knob to control how saturated you want the sound to be. If you have the power amp up pretty high, along with the assault knob, you can get some doom-metal type gains. This amp has bag of tricks, for sure. Really enjoying it.