Hi Ingo, thanks for your question…. The ‘odd behaviour’ that you notice is not so odd… All the circuitry is active, so when you are in 100% compression, with the compressor off, there is gain (or loss) in the circuit. I adjust these compressors so that they should be easy to use in a real situation; feel free to turn the output gain up to introduce some gain into the path. That output gain setting can be moved a little either way to achieve the ‘unity gain’ that you want.
But more important….. how does it sound?? 