X Ambassadors perform at The Fillmore in San Francisco on Feb. 26, 2018. Alessio Neri/STAFF.

SAN FRANCISCO — By adding three soulful backup singers to singer Sam Harris’ bluesy growl on their current tour, Ithaca, New York rock band X Ambassadors added a new gospel wrinkle to their alt-rock sound. Monday at the Fillmore, X Ambassadors, which include talented keyboardist Casey Harris and drummer Adam Levin, sounded like they have a special thing going in advance of their forthcoming sophomore album.

The trio, which has changed guitarists since the tour for 2015’s alt-rock-friendly VHS, has released a handful of new songs in the past year. Their main set at the Fillmore started and concluded with new tunes. “Ahead Of Myself” was a rocker very similar to the band’s earlier material, with booming drums combined with Harris’ growls, but “Joyful” had the singer go full crooner as a melody slowly built under his vocals, beginning with the keyboard and the backup choir, until the drums kicked in and Harris brought the tune home with a saxophone solo.

X Ambassadors perform at The Fillmore in San Francisco on Feb. 26, 2018.

Though it was a rock concert, the song was one of several that featured either sonic or lyrical calls-backs to gospel. “Gorgeous” had the beautiful harmonies alongside a disco beat. So did “Jungle,” one of the group’s biggest hits, which also highlighted Casey Harris’ skillful work on the ivories. By the time his brother began his saxophone solo at the bridge, the song had taken an the vibe of an ’80s hair rock opera. “Loveless” effectively used the singers as well, while X Ambassadors’ newest track, “Don’t Stay” featured an organ-like synth.

“Hold You Down,” a song that has yet to be released, was introduced with a story about Sam Harris becoming estranged, a year ago, from someone with whom he had been inseparable. “I had a falling out with someone I love very deeply,” he said. “Its a mix of emotions. It’s guilt, it’s fear, it’s anger, it’s frustration, sadness and wishing things could be different. I want to say to this person … I still care for you and I still got your back.”

Harris followed that up by performing “Litost” alone on stage, with only his acoustic guitar. The band returned to perform “Unsteady,” which was dedicated to the survivors of of the Florida high school shooting. “We need gun guntrol. We need it desperately. We need it now,” Harris said. “I cannot see this shit again.” The message came across not as a command but more like a plea, or a sermon. With emotions running high, X Ambassadors transitioned into an inspired rendition of “Renagades,” the evening’s peak, with Harrison climbing into the security pit to hug and high-five fans.

New Jersey singer-songwriter FLETCHER opened the show with a 10-song set of empowerment anthems and club-friendly tunes about late nights. Backed by a drummer and guitarist, Cari Fletcher called out the headliners by dedicating her performance of “War Paint” to “the rebels and the renegades out there.” The musicians mostly concentrated on keeping the beat (though it was easy to see the drummer’s enthusiasm as he battered away at the tom drums) and adding texture to each song, giving the singer the opportunity to showcase her voice.

Fletcher performs at The Fillmore in San Francisco on Feb. 26, 2018.

FLETCHER played one of her earliest songs, “Over My Head,” about overcoming hopelessness, and “Princess,” about women overcoming obstacles like abusive relationships, which she dedicated to the #MeToo movement. “Thank you for stepping up and speaking out,” she said. A cover of Cyndi Lauper’s “True Colors” received the simplest, most sparse arrangement (and possibly went over some of the younger fans’ heads), but she regained momentum with the following “You Should Talk” and a new reggae-lite tune that had her spitting lyrics at increased speed. Another newer song, “Undrunk,” got the loudest reception, thanks to to some naughty lyrics. The song was jam about regretting late night mistakes.

She finished with her best-known song, “Wasted Youth,” which she also dedicated to the victims of the Parkland, Florida shooting and the students fighting for gun control.

Follow Roman Gokhman at Twitter.com/RomiTheWriter. Follow Alessio Neri at Windowofcolor.com.