My headphones lack in bass and so I tried to insert an EQ in the master. That works, but I must not forget to turn it off when mixing the composition down to wav.
Next try was another rack containing the headphone-eq and sending to main-audio-out 1/2. I routed the master to "none" with an send-insert to headphone-eq-rack. Then there was no sound in the resulting wav.
Routing the master to audio 3/4 (which is mixed to 1/2 within the hardware) gave me the feeling, that MuLab mixes all audio-outs together at mixdown.
In short: I searched for a solution, that only puts the master-rack's-out into the wav-file, although it does not actually sound, as I listen to the signal via another rack.
Any idea?