A very energetic and emotional Fiona Apple performed for a faithful, sold-out crowd at the Sixth & I Synagogue Wednesday night. (Marlon Correa/The Washington Post)

When Fiona Apple sang, “I just wanna feel everything,” at the Sixth & I Historic Synagogue on Wednesday night, it was easy to assume she already does.

The resurgent 34-year-old singer got physical, ­­throwing elbows and rolling shoulders as if trying to escape an itchy sweater, stomping and kicking as if walking a hot tightrope.

Her gestures were nearly as unexpected, emotive and sensitive as her singing, which pushed to extremes without ever losing its balance.

It’s been nearly six years since Apple last performed in the Washington area, and she’s never relished the spotlight. Her 1996 debut album, “Tidal,” placed her in an elite class of ambitious millennial pop stars who struggled to make peace with fame. But like Apple, many have tiptoed back into our lives. Lauryn Hill is on the road again, D’Angelo is rumored to be finishing a new album and Maxwell’s 2009 comeback was nothing short of triumphant.

Apple has a new album due out this summer, too — the verbosely titled “The Idler Wheel is wiser than the Driver of the Screw, and Whipping Cords will serve you more than Ropes will ever do” — and is currently touring smaller, more intimate venues after making a splashy return at the South by Southwest music festival in Texas two weeks ago. (She was originally booked to visit Washington on March 21 but bumped the gig when members of her band fell ill.)

And while Apple’s flock seemed elated to see the singer perform with such intensity and intimacy Wednesday, the synagogue’s acoustics often failed the music’s finer details.

It’s an in­cred­ibly boomy room that can make the concert you’re watching sound like it’s actually happening next door. So while fragile segments of new songs (“Valentine”) and old ones (“Carrion”), sounded lovely, louder passages disintegrated into a sonic smog that obscured Apple’s voice.

Halfway through the 13-song set, her band seemed to figure it out. The less sound coming off the stage, the better. The pre-recorded backing track of “Extraordinary Machine,” was kept quiet, allowing Apple to fill the room, swan-diving from arid falsetto to plush contralto. Even more stunning was “Every Single Night,” a new song with the “I just wanna feel everything” refrain. Her bellowing voice sounded like a hurricane trapped in a music box.

She closed with two covers: wonderfully woozy reads of the Beatles’ “Across the Universe” and Conway Twitty’s “It’s Only Make Believe.” During both, guitarist Blake Mills eked out little riffs that sounded like birds landing on the singer’s shoulder.

At the band’s most hushed, you could hear the synagogue’s pews creaking as fans craned their necks for a better view — or maybe even the sound of your heart thumping away in your chest. But during “Criminal,” her biggest hit from 1997, it was hard to hear anything but others singing along.

During the final chorus, Apple asserted her ownership, delivering the lyrics in a series of paralyzing snarls. Those singing along froze in their tracks. Nobody in the room was feeling this song more profoundly than her.