Version 12
Version 12 allows you to play around with the Custom amp parameter. Long Press on "Amp" button to go to Sneaky Amps and have fun (don`t forget to select Custom from the list). In the menu bar you can request the recent PreAmp settings from the amp (at the moment it does not retrieve values automatically) -> "Retrieve SneakyAmp from Katana"
https://github.com/katana-dev/docs/blob/master/how-to/use-28-amp-types.md#katana-editor-for-android
The GUI does not update the number values of the sliders, i will fix it soon.
Custom amp values are not stored in the patch. Coming soon too.