The allusions help define the music's emotional character. A striking example involves the Sixth Contrapunctus. Many early-music gurus advise performers to deviate from the page by exaggerating the unevenness of the dotted rhythm of one of the themes, as a French musician of the time might have done. But Phantasm plays the theme as written. Whether you accept that interpretation or not, it shows a rare degree of engagement with Bach's musical thinking.
Phantasm engages other aspects of Bachian style with equal subtlety.
In its sense of which beats to lean on or to glide through, for example, it surpasses the Keller Quartet and many other performers. That accident of stylistic history may explain why Bach fugues sound so natural to us when played by quartets of strings, including Phantasm's violas da gamba. The explanation does not, in any event, lie in the practices of Bach's day. The Phantasm CD should not be mistaken for a period-instrument recording, then, simply because the instruments are old. No one in mid-18th century Germany would have played these fugues with four gambas.