When they first emerged in 1994, San Francisco metalheads Machine Head appeared poised (along with the then-unstoppable Pantera) to lead the cause of American metal, proudly and purposefully, through the second half of that grim, grim, alternative rock-dominated decade.

But, much to their fans' dismay, the band's masterful debut would soon give way to undercooked repetition on their sophomore effort and then, horror of horrors, a grueling descent into nu-metal sellout with their third, before finally crash landing to an uninspired nadir with their fourth.

Within the span of seven short years, Machine Head's proverbial cup had gone from brimming to empty, their few remaining believers understandably holding out little hope for any sort of redemption.

But against all odds, just when the jig seemed to be most certainly up, all of these missteps were summarily erased by the group's stunning fifth album, Through the Ashes of Empires, which saw them rediscovering their roots while reuniting bandleader Robb Flynn with his original Vio-Lence six-string partner in crime, Phil Demmel.

Coincidentally or not, the results marked a return to form in no uncertain terms, with colossal first track "Imperium" single-handedly eclipsing the previous two and a half albums, while simultaneously recapturing the dark majesty and crushing authority of early Machine Head triumphs like "Davidian" and "Ten Ton Hammer." The same was true, to a slightly lesser extent, about ensuing headbangers "Bite the Bullet," "Left Unfinished," and the epic "In the Presence of My Enemies," which collectively showed what could happen when a great band actually follows its instincts instead of half-heartedly following trends.

Not that Machine Head came back from their "lost weekend" completely empty-handed, as incrementally melodic and emotive material such as "Elegy" and "Days Turn Blue to Gray" successfully reenvisioned (and authenticated) a few elements of those failed experiments through the prism of the band's own sensibilities -- not Korn's or Limp Bizkit's.

(In fact, only the rhythmically chugging "All Falls Down" was guilty of a complete and sorry relapse into nu-metal's intolerable whining.) And with the rousing final number, "Descend the Shades of Night," Machine Head delivered yet another monolithic highlight, as steeped in their glorious past as it was promising of the future.