Normally I'd suggest isolating the vocals with a band pass filter or combination or low pass/high pass.

But in this case, the vocal is really too far back to enhance - all it ends up doing is bringing up the guitar (which you already noted).

My only suggestion would be to try overdubbing to vocal. How good are you at imitating your friend? wink


-- David Cuny
My virtual singer development blog

Vocal control, you say. Never heard of it. Is that some kind of ProTools thing?