Help with Triple Output PSU for eurorack

I got a beautiful triple output PSU , used and made by /for Girardin high end Mixing board, as far as I can tell. It delivers 30Amp of +5V () 6Amp of +12V and 3Amp of -12V. These guys have made a lot of eurorack mounted stuff , this is 6U . Still , i’d like to set it up for a large studio case.
The problem is that the 5V has its own ground/OV , not connected to the +/_12V ground. I think it is the rule on pro sound gear to isolate the noisy “logic” 5V bus. I think I read Buchla had the same scheme on their “low impedance” clean PSU
I wonder if it is safe to join both grounds to use on eurorack

I wonder this, too.