At its most basic, the GZII is a Drive, a 3-band EQ, and a Boost, all in a box together. What really takes it to the peak is the ability to put them in effectively whatever order you want.
Much like a real glacier, the many parts of the Glacial Zenith II are able to shift past one another, allowing the pedal to take many forms. Think of the Drive stage fixed at the center, while the other sections can move around it.
The EQ Post Drive let’s you decide whether the EQ comes before the Drive (left position) or after (right position). Drive → EQ is the classic order you’ll find on most dirt pedals, as the EQ directly shapes the sound coming out of your distortion stage. EQ → Drive gives more control over the actual texture of the dirt sound, as you’re shaping your guitar’s tone before it gets dirty. Kinda like the difference between twisting the tone knob on your pedal vs the one on your guitar.
The Pre Drive Toggle then allows you to put the Boost before or after all the other stuff. Put it after (right position) to increase the output volume. Put it before (left position) to slam the Drive even harder, increasing the distortion.
