For classical albums, it is required that all performing artists or key contributors to a work be listed in the artist field. This can include such roles as Symphonies, Orchestras, Choirs, Conductors, Ensemble (e.g., String Quartet), and Soloists.
Please keep in mind all performers must be listed as primary, as the featuring role cannot be used. If you have an artistic director that is performing as a conductor they should be listed as primary on each track they perform on.
Please do not list composers in the artist field, unless they are also performing in some capacity on the recording.