I think the real thing one would need to consider is the spread of an instrument (Or a group of instruments) the the final stereo mix. A first violins section for example could consist of 16 violins and typically spread on the left sixth of the stereo field. A solo violin obviously is one violin that has a definite place in the stereo field. Using stereo and mono tracks makes this scenario very possible. It is then possible to place the soloist in the middle or to the edge of the first violins. This provides a greater level of realism. It is also possible to create a divisi say two smaller sections of first violins playing different parts into different areas (usually close) of the stereo field. Similar can be done with all string sections delivering a much fuller strings section.

Using both stereo and mono tracks gives far more flexibility.

Drums for example are usually placed somewhere close to the centre of the mix. If the drums were mono all drums including toms and cymbals would be coming from the same place. However if they are stereo it is possible to give the drums width then different toms and cymbals would be coming from subtly different areas (depending on the width given). You can get some really nice Tom rolls by spreading the stereo field of the drums.

These are just a couple of examples but the difference can be mind blowing.

Tony

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