you can get all 8 ins and 8 outs working over 2 adat cables (in and out) to your babyface pro
this will not require a firewire connection to computer
the one thing to note, is accessing the internal DSP mixer/totalmix software on the multiface might require you to have a connection to a computer to set the routing, best to contact RME and just double check with them, because it doesn’t look like there are controls on the front panel to do this
also should be no issues using some kind of firewire to usb adapter to have connection to computer to do this especially since its not for audio and just for accessing the settings.
also to note you will be limited to lower sampling rates 44.1/48 to get all 8 channels in and out over single adat