If you are a classical composer and you are achieving, at best, half-way decent "mock-ups" of your work, but what you really want to achieve are artistically accomplished, quality performances of your orchestral music: you should master Vienna Symphonic Library.
If you are a classical conductor, mastering Vienna Symphonic Library puts you in the position to create your own interpretations of the orchestral works you always wanted to record but never had the opportunity to do so - and that with with no artistic compromises, in full accordance with your own musical vision of the work that you are recording.
If you are a music teacher leading a non-professional (student/amateur/semi-professional) ensemble of any kind, with Vienna Symphonic Library you can now create high-quality examples of your musical intention as a guide for your musicians.
