In Logic, the Main Outs on the MOTU 828mk3 Hybrid are seen after the Analog Outputs.
In Logic, go into the “Preferences” menu and select “Audio”
Click on the “I/O Assignments” tab.
For the “Stereo Output” – Select “Output 9 – 10″
After exiting the Preferences, you will now have audio signal from the Main Outs on your 828mk3 Hybrid.