On his fourth studio effort, saxophonist Ravi Coltrane charts a softly expansive, reverently adventurous course that by no means shatters expectations, but never fails to impress. Quietly plugging away at his career, never exploiting his family name and focusing exclusively on deeply intellectual, harmonically complex post-bop, the least you can feel when listening to Coltrane is respect. He's not the "edgiest" player you'll hear, but such tracks as "Variations III" and "Scram Vamp" find Coltrane delving headlong into bumptious, sometimes "skronky" rubato pieces that flirt with free jazz. The sound is reminiscent of early Branford Marsalis whose soprano sax sound also comes to mind on the playful "Coincide." Other tracks such as the romantic and moody "Away" find Coltrane ruminating on his most direct influences, the dusky Joe Henderson and the cerebral Wayne Shorter. Having deftly avoided comparisons to his iconic father in the past, it is pleasing to hear some deeply spiritual cues in his direction as on the expansive opening cut "The Message" in which Coltrane's delicate sax arpeggios recall A Love Supreme. While Coltrane's tenor takes centerstage, the overall concept on In Flux is a group aesthetic that gains strength from the sensitive interplay between pianist Luis Perdomo, bassist Drew Gress and drummer E.J. Strickland.