My technique is that I export voices (either solos or sections) as audio files, and bring them into an audio mixer like Audacity (free) or a paid app that I have. Then I can tweak various settings (volume, fades, reverb, etc.).
The better your score is, the easier it is to do the final mix this way. Since I use this as a proof of scores that will actually be used, I always work from a production-ready Finale score.