The concept here is Hegelian: thesis and antithesis. Bach and Coltrane. The German Baroque master and the American jazz modernist. Or, the art of the fugue and the art of improvisation. The idea was conceived and executed by leader and saxophonist Raphaël Imbert in collaboration with musicians from a variety of different disciplines. From the classical side of the street, there's organist André Rossi and the members of the Quatuor Manfred: violinists Marie Béreau and Luigi Vecchioni, violist Vinciane Béranger, and cellist Christian Wolff. From the non-classical side there's percussionist and singer Jean-Luc di Fraya, bassist Michel Péres, and Imbert himself on various saxophones plus bass clarinet.
The question is: do the thesis and antithesis form a synthesis -- or is it just a conceptual mess? The program mixes works by the two composers in two ways. Sometimes they stand separately, as in the opening pairing of Bach's "Contrapunctus I" from The Art of the Fugue followed by Coltrane's Crescent. Sometimes they run together, as in the medley of Coltrane's Song of Praise and Bach's Jesu mein Freund, or the improvisation on the name B.A.C.H. and Coltrane's The Father, the Son and the Holy Ghost. Bach's works are played more or less straight by Rossi and the Quatuor Manfred, with Imbert improvising on top of them, although occasionally the whole ensemble heads off into free jazz territory. In Coltrane's works, the arrangements stick pretty close to the originals in the sense that the basic "head, solo, head" format is retained.
For classical purists, Imbert's concept will likely seem like an abomination. Why, they might ask, has Imbert layed his squalling and squawking solo on top of the serene Largo from the Keyboard Concerto? For jazz purists, Imbert's concept might just seem extraneous. What need is there for performances of Coltrane classics like Crescent and Song of Praise, which add nothing to the originals, and for howling and honking solos forced on some of Bach's more sedate masterpieces. And jazz purists are unlikely to be interested in Rossi's somber account of Bach's Fantaisie in G minor or in the Quatuor Manfred's solemn reading of his O Welt, ich muss dich lassen. But listeners who relish genre-bending mashups may well find Bach-Coltrane to be a blast.