A friend says everyone needs one Ani record but nobody should bother with two. This discounts the achievement of the first half of DiFranco's career, when she achieved power and clarity on a half-dozen discs. But following Dilate in 1996, which announced her as human even as she brushed something grander, DiFranco has doodled instead of striven, trying on ska bands and mood pieces and "funk" explorations good only for encouraging arrhythmic hippie dances. It's a shame that on this, the most recent of her annual releases, she says nothing new and little well. At first, Knuckle Down seems encouraging. The title track lives up to its promised retrenchment; "Studying Stones" is as gorgeous as -- and wiser than -- "Letter to a John" (from 1994's Out of Range); and on "Manhole," her complaints lift toward a shout-along universality. A few peaks follow, but much of the rest is morose, even featureless. It's laborious work, but it's a start. Pray that Ani '06 remembers that knuckling down is the job of the artist, not the listener.