I share a studio with another musician who uses an RME Fireface UCX on a different computer to mine as well as connected to his own setup, mics and preamps.
I own and use an RME ADI-2 PRO on my own computer connected to my own preamps and inputs but sometimes I would like to use the other musician's setup, which is already connected to his sound card.

I was thinking the best and simplest possible way to do this would be to connect the two cards with an Optical SPDIF cable and put my ADI-2 in AD/DA mode and use it as a slave.
But, when I do this, my DAW (Cubase) still "reads" my card and not his. I've read in the instructions that even if I'm in AD/DA mode, the inputs and outputs are in USB mode. I think that might be my issue?

What I'd like is to use my ADI-2 in slave mode and have all the others musicians setup channel through to my slave card and have Cubase receive outputs sent from my fellow musician's setup.

I feel I'm very close to finding the solution, but I think I need an expert's opinion!

Thanks,

Jorge