Groove - It most likely has nothing to do with calibration. Its probably potentiometers and potentiometer wear. (Anyone notice how often I talk about Pots!??

) Theres a few other posts on here about it. Also, because we give the users 100 fine increments on the knobs, more than any other knobs that we know of, even slight differences will be seen, BUT, settings can also be documented and reproducted. No two pots are matched exactly - they are like snowflakes, everyone different.
We'd be glad to replace your pots for you if they are far enough out of match to bother you. However, we have moved to conductive plastic pots (like most of our competition), and they are no longer very smooth under the setting of FOUR on the knobs. Clarostat discontinued our true logarithmic, molded carbon pots. The new conductive plastic pots tend to be pretty touchy around 1 - 3, but honestly, I dont think many Distressor users work down in that area. It affects FATSO users more.
Thanks for buying and enjoying our products and let us know if there is anything we can do for ya.