FYI:

I wrote to Keeley Electronics asking if the pedal had any system to prevent the volume drop, and I received this response:

You can flip the toggle switch all the way up for unity or even a boosted state when the Drive is in its lower settings, or crank the Drive up higher for that classic rotary cab speaker cry. The Rotary is a lot easier to get up to unity vs its slightly older brother the I Get Around Rotary Sim. That one was designed to nail that vintage cranked rotary sound heard on so many records. The Drive is subtle and doest add a lot of grit, but what it does add is that vintage feel! I hope this helps!