A mother lode of mind-expanding live music from 1970, the six-disc Cellar Door Sessions marks the moment just before jazz-rock fusion perverted itself into a marketing ploy. Here is Miles Davis, sonic seeker, sending desolate streaks of wah-wah trumpet into the unmapped ethos. His bursts of not-jazz galvanize a rhythm team that respects the backbeat yet delights in trampling convention — listen closely and you’ll hear blues cliches and James Brown riffs profoundly and purposefully mangled. On the last night of the run, guitarist John McLaughlin shows up, and the exploration, often guided by Keith Jarrett on gospelized electric piano, reaches higher meta-music plateaus. Though some of the McLaughlin material was used on Live-Evil, much more is seeing daylight for the first time. If anything can possibly redeem fusion, it’s this.