Hello,
thank you for your reply! I solved the problem. I did used “Tascam US1641 (Core Audio)”, but Dorico doesn’t seem to support it. But when I choose “Tascam US1641 (Bit Accurate)” it worked! In all other Software like Logic, Premiere, After Effects, Wavelab, I always use Core Audio instead of Bit Accurate, strange that Dorico needs the other one. And I don’t even know the difference between these two.