That's a good question. At the moment Equator's master volume (found in the Global tab under Preset Master > Level) isn't able to be modulated. This has been a feature request, and we're happy to look into making this an option in a future update. In the meantime, you might explore using the expression pedal's macro to modulate either the level dials in the Mixer tab, or the Levels of the various Oscillators and Samples.
I found now two ways to find a solution for my expression-wish...
1. I was able to modulate all the levels in the mixer tab...
2. (easier) because most of the signals are routet after the mixer in the FX-Section...
Power on the Distorsion FX - put everything to zero - only the level red to 15 % - yellow to 100 %
Now I have a little volume when I switch to the sound - and can get 100% with the expression pedal!
THANK YOU for your Input!