Given the fact that his time in the spotlight lasted little more than four years, Jimi Hendrix recorded a truly stunning amount of material -- so much that even three decades after his death, scads of songs still remain unheard. This four-disc collection goes a long way toward emptying those vaults, unearthing dozens of previously unreleased performances, balanced between new takes on old favorites and long-buried obscurities. Many of the former will primarily be of interest to die-hard fans -- although both "Spanish Castle Magic" and "Stone Free" should turn a few heads -- but the latter, including jaw-dropping improvisations such as "Cherokee Mist" and "Come Down Hard on Me," sound every bit as fresh and fearsome as they undoubtedly did when Hendrix first unspooled 'em. While there's no denying the magic he manifested in the studio, Hendrix was at his best on a stage, alternately challenging, befuddling, and blowing away audiences. The earliest concert recordings captured here -- particularly fierce versions of "Killing Floor" and "Hey Joe" -- date back to the fall of 1966, but even at their nascence, the Experience proved to be fearless and innovative. Those traits became even more pronounced in later live performances, most notably a homespun version of "Catfish Blues" and a suitably eerie "The Wind Cries Mary," both culled from a 1967 gig in Paris. Yes, some of the stuff slathered across the four discs could be considered more novel than revelatory -- including odd runs through "Sgt. Pepper's Lonely Hearts Club Band" and oldies such as "Johnny B. Goode," which was previously released on Hendrix in the West -- but even in those less significant moments, his sheer musical mastery elevates the material beyond mere cover-band fodder. The open-ended genre-bending that provides a coda for this chronologically sorted set ends things on a note that's both exhilarating and saddening: The mind-blowing music itself is so staggeringly visionary, it can send your spirit soaring -- until, that is, you are humbled by thoughts of what might have lain ahead.