This seems like a pretty good resource. I found the answer I needed in here - of course, I haven't applied it yet since I am at work. But it makes sense what they are saying (the mixer levels in my computer aren't ticked right or adjusted correctly, that's why the samples are silent).
Codemasters Support Community for MTVMG
Cheers!
Codemasters Support Community for MTVMG
Cheers!