When My Morning Jacket's popularity was cresting in 2007 — opening for Bob Dylan at Colorado's Red Rocks Amphitheatre, headlining Chicago's Lollapalooza and drawing reams of "best live band in America" chatter — Jim James' cover of choice, the one song he didn't write that made it into all of his sets, was Curtis Mayfield's "Move On Up." James sang it with gusto. Ever since 2005's Z opened with "Wordless Chorus," a falsetto slab of ecstasy and agony, his inspiration wellspring has shifted from folk, country and arena rock toward soul, funk and deep-track R&B. It hasn't always worked out ("Highly Suspicious"), but when it does, it's glorious ("Only Memories Remain"). His new solo album, Eternally Even (Capitol), feels like the summit of that pratfall-marked climb. Instead of indulging his urges in momentary bursts, he lowers himself into them like a hot bath, soaking in a druggy reverie of lowest-key vocal deliveries, reprising bass melodies and light-tripping benevolence. The payoffs are numerous, but they're headlined by "Here in Spirit" (a glitch-scratching "What's Going On") and "We Ain't Getting Any Younger," a 10-minute, two-part, organ-donation drone suite that recycles the bulletproof eight-note bass lead that opens the album (that circuital return is among my favorite moments on record this year). It's a stoned-warm classic in the making. Twin Limb opens and backs James. Tickets $33.50.