Finally finished this baby! Got slightly confused about wiring J1 connector on the main board and of course wired it the wrong way around. After finally finding the error (weeks passed), the mic sounds really really sweet. Thank you mihi_fuchs for the good work! And maybe leave a small remark in the build guide about wiring J1. I thought pin 1 was where J1 is printed. Now I know!
Cheers
Max
Cheers
Max