Ted The only reason why you may ever need to export a wav is if the quality is actally needed at the other end. If you are just looking for someone to add a track to an existing project an Mp3 should be good enough for them to work from. It is the single track file you get back with the new stuff that needs to be of this quality. This track has to be just the stuff your friend lays down. If it contains anything else eg a full mixdown then it cannot be edited properly when you get it back.