I just run the line out from my game rig into the line in on my workstation, and set it to monitor. Not sure where your music comes from, but if its on the workstation computer, it should all mix together.
You only have 2 physical boxes. Just use a male to male 3.5mm cable and output to the input on your workstation. Set the workstation to monitor the input. Adjust volume levels in software on the workstation.
some low end systems have a combined mic and line in. But most current stuff has separate channels for mic and line in. You can monitor line in without re-feeding it through the mic. Mic is red. Line in is blue.
Hmm. whatever. Not sure what/why you cant get it to work. I think it should work just fine. Maybe you aren't doing something correctly. Play around with settings.
Never said that it doesn't work as described. I was explaining what I plan to do, and gave a rough outline, asking if it'd work and if there was a better way.
Yeah I read it. I don't see any complication. I've been running separate workstation and game rigs since the 90s and I have done the same thing and it works. Even with VMs it shouldn't matter. Worst case you mute the input on some of the VMs to prevent a feedback loop.