The Tesseract Boost/Preamp is an adaptation of the TC Electronic Integrated Preamp, a boost & EQ from the late 1970s. The Integrated Pre is so named because it’s designed to connect directly to your guitar, which is why the original unit did not have a bypass switch.
The Integrated Preamp gained fame as the secret behind Meshuggah’s guitar tone in the 1990s. The boost was perfect for pushing the front of their Mesa/Boogie Dual Rectifiers and the EQ can cut bass for a tighter driven tone.
The original unit could run on as much as 32V using an external supply, or it could operate at the standard 9V using a battery. Since 32V supplies are hard to come by, the Tesseract Boost/Preamp includes an on-board charge pump that quadruples the input voltage (minus a few diode drops), allowing a 32V operation from a standard 9V supply.
The only other modification is the removal of a pop-suppression circuit at the input. This is designed to prevent the loud pop when the input jack is first plugged in. It’s useful in the original unit that connected straight to the guitar since the preamp would reasonably be plugged & unplugged in a live setting. However, in pedal format, the suppression circuit has no function other than to increase the current consumption as it is always bleeding some of the supply voltage to ground. There is no impact to the tone or functionality if it’s omitted.