Hi,
is it possible to receive Midi from my Midi Keyboard via USB, when plugged in Overhub, while my Digitakt is also plugged in Oberhub ? I ask this question, because as almost every Apple user I ran out of USB-ports.
Thank you for your answers ! 
any usb hub can send USB midi to/from the attached computer, but the hub/overhub will not connect them directly, you do need a host or/and a way(e.g. daw) to connect them on a computer
Ok thank you, so it will work, if plug my Keybord and my Digitone in the Overhub and then plug the Overhub in the USB port of my Mac Book(as host), where I record it with my DAW, right ?
Tanks again for the quick answer