It’s been nearly 50 years since Maria Callas, the most admired and photographed opera singer of the 20th century, passed away from a heart attack at age 53.

If you listen today to recordings by the Greek singer known as “La Divina,” you can hear both the power and the sharp edges in her voice. She didn’t have had the most beautiful vocal instrument, but no soprano ever sang with more passion, ferocity or exhaustive preparation, and the suffering, sacrifices and heartbreak she endured in her personal life could have made for its own opera libretto.

Instead, Callas’s story is told in “Master Class,” Terrence McNally’s Tony Award-winning 1995 play, which opened Saturday night in a co-production by The Roustabouts Theatre Company and Scripps Ranch Theatre at Alliant International University. He based the play on the real-life master classes the retired Callas taught for opera students at The Juilliard School in Manhattan in the early 1970s.

In between harshly, but honestly, coaching three students in their aria performances, the demanding Callas talks to the “classroom” audience about her difficult youth, hungry years during World War II and her tireless work ethic. She devilishly casts shade on her fellow sopranos and often slips into dreamy reveries about her past, which are accompanied by recordings of her singing and projections of photos from her peak years.

This is the first time “Master Class” has been professionally produced in San Diego in 10 years, and San Diego actor Sandy Campbell is reprising her role as Callas, which she first played in 2015 at San Diego’s now-defunct ion theatre.

In my 2015 review of Campbell’s performance, which earned a top acting award from the San Diego Theatre Critics Circle, I praised her passion, focus, honesty and vunerability. A decade later, I think she’s even better in the part. Her Callas today is more emotionally cool, more fragile, more subtle, more fluid in her movement and more battle-hardened by the public humiliation Callas suffered when her wealthy lover Aristotle Onassis left her to marry Jacqueline Kennedy in 1968.

Roustabouts artistic director Phil Johnson directed this production, which brings many welcome moments of humor as well as more audience interaction to the story than I remember. He has also surrounded Campbell with a talented cast, led by Kyle Adam Blair as Manny, the Juilliard piano accompanist playing for the student singers.

Sara Frondoni shows impressive acting and singing range as Sharon, the ultra-nervous young soprano who flees the stage in her first encounter with Callas, then returns to gradually work her way through the letter song in Verdi’s “Macbeth” with Callas.

Abigail Grace Allwein makes a nice acting transition as Sophie, an unprepared young singer who withers, and then grows, under Callas’s tough but illuminating instructions on how to sing Amina’s final aria from Bellini’s opera “La Sonnambula.”

Ben Read is exuberant and irrerepressible as Anthony, a talented young tenor who eventually wins over Callas with his performance of Mario’s painting aria in Puccini’s “Tosca.”  Tim Benson also earns some laughs as the stagehand who grows increasingly exasperated with Callas’s requests.

Dixon Fish designed the college auditorium scenery, Dawn Fuller-Korinek dsigned costumes, David Kievit designed lighting and Ted Leib designed sound and projections.

Today’s audiences may not know Callas or her music very well, but the dramaturgy notes by Tim Botsko in the printed program will greatly enhance the viewing experience of “Master Class.”

‘Master Class’

When: 7:30 p.m. Fridays and Saturdays; 2 p.m. Sundays. Through Dec. 14

Where: Legler Benbough Theatre, 9783 Avenue of Nations, Alliant International University, San Diego

Tickets: $30-$52

Phone: 858-395-0573

Online: theroustabouts.org