If you want to look like one rad editor for your composer, output a cut for them with all dialogue (DX) panned to the left and music (MX) and sound effects (SFX) panned to the right. This will show them you are a pro.
To do this in FCP, I would just change the pan on the tracks that contain DX to left and the MX and SFX to right. This is one reason it is so important to make sure your tracks are organized throughout your edit. Try to keep dialogue on tracks 1-5, SFX on 6-12 and music on 13-16 (or some variation of that).
In Avid, the easiest thing to do is make a mono audio mixdown of the tracks that contain DX and then another for MX/SFX. Then you only export the cut with those tracks and pan left and right respectively.