Thank you for such a quick reply.
"You can group two pairs of ls-50w together "
This is good news. One step closer to what I might end up wanting. Thank you so much!
I found the link: Custom multichannel mappings
Problem is, as far as I researched, only NAD produces surround preamps that are also Roon endpoint.
Current model, NAD T187 is totally over-kill.
I am not sure if I can install Roon on 2nd hand units on Ebay either.
So I have to attach some hardware as endpoint to other preamps like Denon. So, if I can skip PC-endpoint and amp, it would be better. After all, Roon can play into LS50W directly.