Hi Christoph.
To test this, I set the compressor stomp in slot A so that everything is at zero or (100% where necessary).
There is a Clean Boost in slot B that is NOT enabled)
If the Compressor is the only stomp that is enabled, I can switch it on and off with no change in the tone or volume. (EXPECTED RESULT)
When the Compressor is OFF, the volume increases normally when I activate the Green Scream in Slot C. (it is set to gain = 2 and vol = +1.5) (EXPECTED RESULT)
If I then switch the Compressor ON, the volume actually goes down.. (Compressor and Green Scream are the only two slots active) (UNEXPECTED RESULT)
This is just an example of the headaches I am having with this simple fx chain. I am not able to reasonably predict what my overall volume will be with different combinations of these three, in some cases it is excessive volume increases, in others the volume goes down.
I have set my input sense for 4 different guitars and it happens with all 4 of them.
I have tried a few different rigs with different gain and it happens with them. (rigs are purchased)
Thanks for your insight.