Hello everybody !
I actually have OSMC with a DIGI+ classic, I use Airplay but the quality it is not realy very good (and it don’t work with iOS 11)… 
I have already try Volumio but i can’t have it with OSMC… I have another pi in a drawer and I question myself, if I use airplay of volumio to send informations by my DIGI+ classic to the DIGI+ I/O on my OSMC pi to my amp while being able to use OSMC like source to the same amp does it works ?
Or the reverse, I use OSMC to send sound information to digi+ classic to digi+ I/O on my volumio to my amp. 
My question is Volumio can support that and if yes, how ?
If not I can do it with a switch but for s/pdif signal it is not coolest and affordable… 
I have put a .pdf to show what I want if it is more clearly.
Thank you