Reading all of these posts I would recommend you CALL tech support. If I understand your questions I and many others have been doing this for years with BIAB but with only ONE keyboard at a time. Everytime I get no sound I have gotten up and running with sound in 5-10 minutes when I call the tech support line. I try and figure out stuff on my own but after a couple of hours of getting no where I call for help and it works! Don't mean to put down the helpers here but when someone can talk you through it or even get on remote control and fix it they seem to spot what the problem is faster than when I'm trying to explain whats going on in my weak untechie way.

Dell 610 dual Monitor, win 7-10, Sonar Plat, ProTools 10 & 11, Reaper 4, BIAB/real Band 2022, Easy Drummer, Superior Drummer, Kontact Essentials, Personnel Orchestra, Korg Legacy Analog & Digital