In that year he formed PHANTASM. Since then he has devoted most of his performing efforts to appearances as part of the group, which gained quick international recognition when its debut recording of Purcell's Fantasies for viols won the Gramophone Award for Best Baroque Instrumental Recording of 1997. Meanwhile, Dreyfus continued his teaching and scholarly pursuits. His book Bach and the Patterns of Invention (Harvard University Press) won the Otto Kinkeldy Award of the American Musicological Society as the most distinguished book of 1996. The other American in the group is Wendy Gillespie. She is a graduate of Wellesley College, the Amsterdam Conservatory, and New York University. She began an active performing career as a specialist on Baroque and Renaissance string instruments in the early 1980s in New York. Then came a period in England, where she joined Dreyfus in PHANTASM. She has toured numerous parts of the world and participated in concerts with several leading Baroque and Renaissance ensembles, including the Taverner Players, Theatre of Voices, Ensemble Sequentia, and the New York Pro Musica Antiqua. Among the string instruments she plays, she is fondest of the viol, and founded the viol ensemble Les Filles de Ste-Colombe. She is now a professor at the Early Music Institute at Indiana University at Bloomington, teaching performance practice, Renaissance notation, and early strings. Jonathan Manson was born in Edinburgh, Scotland. His teachers in cello were Jane Cowan of the Cello Centre in Scotland, Steven Isserlis and David Waterman in London, and Steven Doane at the Eastman School of Music in Rochester, NY. It was in America that he became interested in early music so he went to Holland to study with Wieland Kuijken. In addition to being a member of PHANTASM, he is principal cellist of the Amsterdam Baroque Orchestra. The fourth member is the Finnish cellist and gambist Markku Luolajan-Mikkola, who studied cello with Arto Noras in Helsinki and also went to study with Wieland Kuijken when he developed an interest in playing older music. He teaches at the Sibelius Academy in Helsinki and is an active chamber musician. He won a Finnish national award for excellence for a 1994 recording of music of Marais.
The core group of four players is joined by other colleagues as needed, depending on the music. In 2009, the group collaborated with the Magdalen Chapel Choir and in 2010 was named consort-in-residence at Magdalen College.