[marina]

This is a cheap fix, but I used to just edge the computer speakers close to the mic and do it that way. This would probably only be a quick fix for you, since I doubt that with that expensive mixing board that you'd be content with shitty sound for long.

Also a quick fix, but I seem to recall that in audacity you can make a secondary track, unmute it and drop it along the timeline in the secondary track, and continue talking over it on the primary track. You have to be wearing headphones or you get weird echo, and you can't pause it to talk about it, but you can talk over it.