Of all the popular '70s progressive-rock acts, only King Crimson insists on actually progressing. Thanks to a constant string of strategic line-up changes, no two editions of the group have sounded quite the same, and what few prog-rock peers remain intact have long ago been left in the dust. It all seems like part of King Crimson leader Robert Fripp's grand plan: Keep moving forward, and eventually everyone will be left behind. When King Crimson last resurfaced five years ago, it was what Fripp deemed a "double trio"—that is, two drummers, two bassists, and two guitarists. It was a magnificent beast that couldn't last, but Fripp made the most of it by breaking the band up into smaller units and touring, and the on-the-road research and development seems to have helped the new, pared-down version of King Crimson. Now, Fripp is calling the band—which, with Fripp, includes singer-guitarist Adrian Belew, bassist Trey Gunn, and drummer Pat Mastelotto—a "double duo" rather than a quartet, but the term isn't that ingenuous. Each member, with his wide array of pedals and effects and boundless creativity, has the uncanny ability to sound like many players at once, a subtle sort of virtuosity rarely heard in rock bands. Considering that this edition of King Crimson is essentially an abrasive pop group, the smaller unit does a nice job navigating the heady arrangements while keeping the melodies intact. The ConstruKction Of Light sounds like a cross between the early-'80s quartet edition of King Crimson and the recent, more muscular model, which in some ways is more of a step sideways than a leap forward. But "ProzaKc Blues" is still an aggressively confrontational way to open the band's 12th album, and Belew's incongruous Beatles-isms are integrated with relative ease into such songs as "Into The Frying Pan," "The World's My Oyster Soup Kitchen Floor Wax Museum," and the second half of the title track. "Larks' Tongues In Aspic—Part IV" is unveiled here, too, a fact that should make fans of Roman numerals and fancy guitar interplay ecstatic.