The Kronos Quartet was at Zankel Hall on Friday with a typically eclectic program that included new works drawing on jazz, psychedelic rock and Nordic folk music. The vibrant performance was not only the ensemble’s return to a space it reliably fills with devoted fans; with the quartet’s ranks refreshed by three brilliant new players, it also felt like a comeback.

In recent years, the aging ensemble — founded in 1973 by David Harrington, who continues to lead it as first violin — sometimes seemed to have had slid into an identity crisis. The Kronos brand was still strong: Ambitious commissions kept pushing the boundaries of quartet music, resulting in more than 1,000 new works and arrangements drawing on every imaginable style. In the run-up to its golden jubilee, the ensemble initiated a commissioning project, 50 for the Future, and made the sheet music to all 50 pieces available free online.

But the quality of the playing had become inconsistent. And the spoken introductions the players offered at concerts felt perfunctory and tired. When the violinist John Sherba and the violist Hank Dutt, who had been in the lineup since 1978, retired last year, the quartet might have disbanded. Instead, Harrington brought in fresh talent and — judging by the music-making on Friday — strong personalities. The quartet’s middle voices now belong to the violinist Gabriela Díaz and the violist Ayane Kozasa, who join the composer and cellist Paul Wiancko, who came onboard in 2022.

During the kaleidoscopic first half of the concert the two women asserted themselves as the quartet’s engines of emotional intensity and a newly lustrous, rich sound. This came through most powerfully in Aleksandra Vrebalov’s incantatory “Gold Came From Space,” which gradually grows in sonic density and expressive intent of tremulous whispers. Time and again, Kozasa’s viola stole the spotlight with its absorbing mixture of lyricism and throaty candor. She channeled Nina Simone’s tough-nosed tenderness in Jacob Garchik’s arrangement of “For All We Know” (composed by J. Fred Coots) and set the tone for Wiancko’s arrangement of Neil Young’s protest song “Ohio.”

Two songs by Sun Ra, “Outer Spaceways Incorporated” (wittily arranged by Garchik) and “Kiss Yo’ Ass Goodbye,” in a psychedelic arrangement by Terry Riley and Sara Miyamoto, sparkled with experimental glee. That exploratory zest had always been a hallmark of Kronos. But the heart-on-sleeve directness the group brought to Viet Cuong’s stirring “Next Week’s Trees,” in which the quartet sometimes sounds like a giant harp, felt new.

The second half was taken up by a single work, “Elja,” by Benedicte Maurseth and Kristine Tjogersen. Maurseth, who joined the Kronos players for the performance, is a master on the Norwegian hardanger fiddle, a violin-like instrument with four extra resonating strings and a curved neck and carved scroll that evokes the bow of an ancient ship. For the 45-minute piece, which also featured recorded nature sounds, the Kronos players switched to hardanger versions of their own instruments. (The viola and cello fiddles were specially built for Kronos by the Norwegian luthier Ottar Kasa.)

Forty-five minutes felt too long for this extended study in stillness with breathy harmonics animated by rippling arpeggios evoking a wind harp set up in a desolate landscape. But the collective sound the Kronos produced, even with these unfamiliar instruments, was cogent and unified.

For a half century, Kronos has shaken up expectations. With the current lineup, it has the potential to go in new directions, including — perhaps surprising in a group that long cultivated a certain brand of cool — the ability to dig for a deeper emotional connection to sound.

Kronos Quartet

Performed Friday at Zankel Hall