1. solved. Thanks.
2. ups, once I R-enabled the Mac Audio Track for monitoring (while having Software Monitoring activated) I got an audio loop feedback. directly disabled it. I tried solving it by pulling down Stereo Out Fader in the right inspector channel strip (still can hear Mac Audio) and then R-Enabled the Track again, this time no audio loop feedback. Then adjusted the EQ Levels, but didn't hear a change in the live feed. So for now I R-disabled Mac Audio and pulled up Stereo Out again.
I'm using a MixPre-10T as Audio Interface with lastest Firmware on MacBook Pro Late 2013 (OS 10.12.6). Here are some screenshots from my Logic (10.4.4) Setup:
Input Output Settings: https://www.dropbox.com/s/m9nmkxeeglyuikl/Screen%20Shot%202020-05-02%20at%2016.47.12.png?dl=0
Environment Window: https://www.dropbox.com/s/tub9olssjsk3ocw/Screen%20Shot%202020-05-02%20at%2017.17.47.png?dl=0
Main Window: https://www.dropbox.com/s/bktivnxvxosavaa/Screen%20Shot%202020-05-02%20at%2017.22.06.png?dl=0