The original Performance: Rockin' the Fillmore was one of the classic double-live albums of the '70s: a two-LP set from a band that had yet to have a hit but were earning a reputation as in-concert monsters, grinding out a living on a circuit that brought them from coast to coast in America. It was, by design, the opposite of what Steve Marriott experienced as the leader of the Small Faces: this was heavy, improvised blues rock where live moments trumped the studio. 1970's Humble Pie and 1971's Rock On suggested the churning improvisations of Humble Pie at their peak -- and not long afterward they'd streamline their jams into something easier to digest -- but the Performance LP captured the group at their elongated best, playing for upwards of a half-hour without a care in the world. Such instrumental indulgence was commonplace in the early '70s, but disappeared in the decade afterward, so Omnivore's enthusiastically exhaustive 2013 box set Performance: Rockin' the Fillmore - The Complete Recordings winds up capturing two distinct phenomenon: Humble Pie's peak as an improvisatory blues-rock band, but also the era when rock bands who weren't the Grateful Dead could ensconce themselves on-stage and play endlessly, not caring for the audience's reaction as much as their own edification. Omnivore's four-disc set rounds up the entirety of the band's four-night stint at the Fillmore East and, as such, each disc is almost identical in attack on the set list. Every night, the band runs through "Four Day Creep," "I'm Ready," "I Walk on Gilded Splinters," and "Hallelujah (I Love Her So)," then ends with some combination of "Rollin' Stone," "Stone Cold Fever," and "I Don't Need No Doctor." This repetition means the complete Performance can be too much to take in one sitting, but its indulgence is what's appealing; listen to this in batches and not at once, and it's easy to appreciate the group's elongated, elliptical boogie and, particularly, the back and forth between Marriott's pirouetting frontman act and Peter Frampton's muscular leads. Soon, this kind of never-ending jam fell out of favor and that's why this reissue is so valuable: there was a time where this kind of self-congratulatory improvisation was not only accepted but expected and Performance: Rockin' the Fillmore - The Complete Recordings not only captures that point in time, but in its exacting detail it illustrates how this self-satisfied instrumental exploration could be a very good thing.