The fourth volume in the ongoing Miles Davis live Bootleg Series, 2015's Miles Davis at Newport: 1955-1975 is a four-disc anthology that brings together all of the legendary trumpeter's live recordings captured at the storied Newport Jazz Festival. Founded by organizer George Wein in 1954, the Newport Jazz Festival grew into one of the premier music festivals in the world, thanks in no small part to Wein's longstanding association with Davis. With Wein's support and famous dedication to encouraging artistic experimentation, Davis would return to the festival throughout the most creatively vital years of his career. Although he first appeared at the festival in 1955, unbilled, ostensibly as part of an all-star group featuring pianist Thelonious Monk and saxophonist Gerry Mulligan, it was his star-making rendition of "'Round Midnight" (the microphone buried deep in his trumpet to overcome sound-system issues) that landed him a record deal with Columbia and marked his ascent as one of the most innovative and important figures in music history. Miles Davis at Newport details the association between Davis and the festival, each performance serendipitously documenting his ever-morphing sound, from swinging cool jazz in the '50s to aggressive, free jazz-influenced modal bop in the '60s and finally to funky, acid-soaked fusion in the '70s. As with the previous Bootleg Series sets, many of the tracks on Miles Davis at Newport have been available either officially or unofficially in some configuration for decades. Nonetheless, this collection does contain several previously unreleased cuts, including an epic 1966 version of "Stella by Starlight." Showcasing Davis' transformative second great quintet with pianist Herbie Hancock, saxophonist Wayne Shorter, bassist Ron Carter, and drummer Tony Williams, the track begins as an atmospheric rubato ballad and ends with Davis and his group having blown out the walls of the song's form with frenetic glee, a move that foreshadows the darker, psych-rock-infused sound Davis would debut with his next appearance. Captured just six weeks before the recording sessions for his landmark fusion album Bitches Brew, Davis' 1969 Newport date is a roiling, funky performance, marked by Chick Corea's dewy Fender Rhodes and Jack DeJohnette's whirlwind percussion. By this time, Davis had eschewed the jazz standards-based lyricism of his 1958 appearance, favoring instead an open-ended, groove-oriented sound punctuated by the outward squelch of his horn. The collection ends with three of Davis' post-Bitches Brew performances, two recorded in Europe in 1971 and 1973 and one at New York's Avery Fisher Hall in 1975. With Davis' trumpet slathered in the sticky swell of his wah-wah pedal and his group featuring saxophonist Dave Liebman and others, including not one but two electric guitarists with Pete Cosey and Reggie Lucas, these performances mark the apotheosis of a creative journey that began at Newport two decades earlier.