SOLVED!
I found the issue!
As expected it was me making a dump mistake... xD
I forgot to set the DIR and STEP pins as outputs in the code. Apparently the DRV8825 does not care, but the MC2209's did. So just remember to set the control pins as output and it works xD
I gotta say, these drivers impress me! The clock is litteraly silent now. Absolutely no motorsound what so ever, none!