I do appreciate all your efforts. I will also stop by the booth at NAMM for a hands-on demonstration with one of your associates. And the primer I refer to is the link you provided, https://connectvst.com/. In the meantime, some progress. I set up an empty project and had the artist swap out his brand new Presonus interface for and older M-Audio he had about. I checked the routing and CR setup per the primer and, after selecting the correct input from the interface (input 1) and lowering the M-Audio buffer to 256, he was able to hear the music mix I imported and his voice in reasonable sync as did I. The TB worked as well. Not at all sure what the difficulty is with the Presonus as it functioned unpredictably. Maybe it doesn’t like the latest Mac OS. Unfortunately, Cubase crashed and did not retain the saved session nor any .bak’s. But before this happened, I began to play with the VST mixer levels and EFX. I was not able to hear any reverb, etc. but I hope to get this working next. Well. at least it’s a step in the right direction. Cheers.