As a singer/composer who’s delved into opera and Shakespeare sonnets and once performed a Judy Garland tribute, Rufus Wainwright certainly knows how to tackle a concept. That said, the show that he brought to the Emerson Colonial Theatre on Wednesday seemed a tad open-ended. The “All These Poses Tour” alluded to his sublime 2001 album Poses, yet a (20^th) anniversary tag lined up to his 1998 debut.

Those ornate pop albums set the course for the talented scion of Kate McGarrigle and Loudon Wainwright III and, as it turned out, he meant to feature both live. The first set of the two-hour-plus show was mainly devoted to 1998’s Rufus Wainwright — and he began promisingly with the breezy “April Fool” (piping “And you will believe in love”) and impressionistic “Barcelona,” backed by an empathetic five-piece band as he strummed acoustic guitar in a top hat and pinstripe suit.

Still, even in a shuffled song order, the material from that album began to lean toward the maudlin and monochromatic. Wainwright made a wise choice to skip a few of the tunes and spring one cover and one new original to close the half. He turned Joni Mitchell’s “Both Sides Now” inside-out with emotive dynamics, the line “I’ve looked at life from both sides now” perhaps drawing experience from a drug-fueled nadir early in his career. And he shared “Sword of Damocles,” a song inspired by the midterm elections with a “message to change the world,” taking its name from the classical tale of a courtier with a blade dangled over his head to signify the perils that come with power.

But the night’s main course came in a full, in-sequence rendition of Poses, sharpening Wainwright’s melodrama in musical and theatrical terms. He strode to his piano like a hobo queen in a glittery rag-tag coat and hat to open the second half with “Cigarettes and Chocolate Milk” and continued to unspool Poses’ wider palette. He donned a feathery black cape to inhabit the Gershwin-esque title track with his luxurious voice, let the band fill the folds of the creeping, sweeping “Shadows” (where he sang “I could be a great star, still I’m far from happy”) and returned to guitar for the jaunty “California.” His restrained band, including guitarist Gerry Leonard (David Bowie) and bassist Paul Bryan (Aimee Mann), truly stepped forward in the ominous, near-proggy swell of “Evil Angel.”

“It’s very difficult to keep the line between the past and the present,” the singer said before “Grey Gardens,” quoting the words of the eccentric New York socialite Little Eddie who inspired that song. And he gracefully managed that trick – and capped the night with a last bonus in his dreamy, resonant take on the Beatles’ “Across the Universe.” Not for nothing, Wainwright’s world has changed, but the return to his underappreciated jewel Poses made this evening timeless.