Why would you make a booster that has a MINIMUM of 6db boost? Some people need less, some people more so why not just start boosting from 0db!?
To fix this I stuck in a 100k linear pot to replace the 25k rev log pot that is inside. Now you can start boosting from 0db up! Linear pot has a poor sweep though so if you want to make it perfect you need a rev log pot. I rarely adjust mine so I didn’t mind the sweep… Alternatively you could wire a 100k log pot in reverse (swap the 2 outer wires) but in that case the boost control would also work in reverse. 50k pot would make the minimum boost 3db. You can buy 100k anti log pots online for example at Musikding and Banzai music.