What do you call an opera without a live orchestra?

		'The Voluptuous Tango' Where: Quantum Theatre at The Mellon Institute, Fifth Ave., Oakland. When: Through April 2; Wed.-Sun. 8 p.m. Tickets: $15-$22; 412-394-3353.

No, not a cash-strapped production, a la Pittsburgh Ballet. Instead, this is the American premiere of "The Voluptuous Tango," a Quantum Theatre adventure, a mini-opera with dancers provided by Attack Theatre, all in collaboration with Carnegie Mellon University, which provides a performing space at the impressively colonnaded Mellon Institute.

But what is it, really? Quantum describes it as "an opera bouffe in 11 scenes ... a surreal musical journey through Italian Futurism," dramatizing an imaginary meeting between Lenora Nemetz as famed dancer Isadora Duncan and Richard Morris (the Welsh baritone who starred in Quantum's "Kafka's Chimp") as Marinetti, father of Futurism.

More poetically, the Quantum pitch says, "with operatic chorus revealing hidden agendas, history is humorously rewritten according to the law of the tango. ... [It's] a tempting tale, where fried pink roses grace the dinner table and seduction is the main course."

As far as I could tell, neither fried roses nor seduction were on the menu at Shadyside's Elbow Room during two recent late-night discussions with noted English director Di Trevis -- unless it was the intellectual seduction of the theater critic.

On the first occasion, composer Dominic Muldowney (the opera's text is by David Zane Mairowitz) was also there, paying a flying visit from London. He happens to be Trevis' husband, which is why it's not happenstance at all that she's directing "Tango," but the contrivance of Quantum's Karla Boos, who secured Trevis by piggybacking on her assignment to direct "As You Like It" at CMU in just a few weeks.

If not exactly British theatrical royalty (that's the Redgraves), Trevis and Muldowney are Life Peers, at least. With an emphasis on the classics, Trevis has directed extensively for the Royal Shakespeare Company, the Royal and Scottish Operas and, most of all, the National Theatre, where she was the first woman to lead a constituent company.

Muldowney began in 1975 as assistant to the NT's first music director, then filled the post himself, 1981-97. As a result, he has composed scores of theater scores, along with some 30 scores for movie and TV. He also has a range of concertos (piano, saxophone), a string quartet and varied pieces for voice and instrument.

Most impressively, he wears a hat that belonged to Samuel Beckett, and even let the critic try it on (it's too small). That's another seduction.

The hat was given him by composer John Cage, saying, "some mad Irishman gave me this."

Trevis and Muldowney really have been a package deal: Muldowney is also writing music for Trevis' "As You Like It" at CMU. And Boos managed to get a ride on CMU's dime by scheduling her casting for "Tango" on the same November visit when Trevis cast the CMU show.

So what exactly is "Voluptuous Tango"? Opera theater? An art musical? A sung play?

It requires operatic virtuosity, Muldowney says, but also a "speaksinging" quality, like Sondheim or Kurt Weill.

"The opera houses and young opera companies want to use stage actors," Trevis says. "They want the words to be understood, not just to be beautiful." She makes the analogy to mid-century British acting, which valued mellifluence. She herself is of the theater generation post-1956, when John Osborne's "Look Back in Anger" signaled the arrival of a grittier truth on stage.

Trevis, Muldowney, Boos and the baritone, Morris, who was also there, all agreed that singing is really an acting problem, which is why they're so intrigued by Nemetz. She's no opera singer, but she has everything else. Muldowney is impressed: "I'm not flanneling you at all. ... [to Trevis] You could find a major project for her."

Coming from a working-class background (she humorously classes herself now as "working-class arriviste bohemian intelligentsia"), Trevis studied anthropology at the University of Sussex, "and then I threw it all away" and became a successful actor, mainly at the Glasgow Citizens Theater, then at the NT and in London's West End.

"I was happy in theater, but I was unhappy as an actress. It was the wrong job." She probably went that way because when she was coming up, there still weren't many women directors in England. So in 1981, she became a director through the simple expedient of attending a directing workshop and declaring herself one. She optioned a play and staged it, and she was off and running.

What makes her happy about directing?

"Everything. There is no down side. It's the job God meant me to do. ... I could have also been a marvelous charlady. [Big laugh.] I can't think without doing a bit of low dusting or ironing. I come from a long line of charladies" -- Dublin Irish who moved to Birmingham at the turn of the past century.

Dusting and ironing isn't entirely unlike directing. But neither is anthropology, which she hasn't thrown away at all: a director also "examines a tiny segment of society" -- especially the way Trevis directs, which is "to just sit in the rehearsal room and really, intuitively see what's going on," as opposed to misguided directors who come in with a pre-formed idea of what they want.

She describes directing at the NT and her music director husband, having sat in on other directors' work, coming into her rehearsal and whispering urgently, "when ... are .., you ... going ... to ... START?" "I'm well on my way," she'd reply.

"Musicians can pick it up and play it," she explains. "Actors can't; that's why you have weeks to rehearse."

She says the key is that as a director, "you're not truly creative, you're a craftsman. I don't start from a blank piece of paper." She reckons she has "good old-fashioned British leadership qualities," plus a sensitivity to the group, which is the true creator.

Probably Trevis' most famous work is the "Remembrance of Things Past" she directed at the NT, which she adapted from Harold Pinter's famous unfilmed screenplay of Proust's novel: "I had the idea, I adapted it with Harold, I directed it -- and I acted in it!" That was in an emergency one night during the run, 19 years after giving up acting.

Knowing acting helps her as a director. Knowing theater helps her husband as a composer. "He had the latest technology at his fingertips at the NT," says Boos, "but he's more connected with the performers, so he can put all this technical proficiency at their service."

With "Tango," the technology is invisible. Not only is there no orchestra, there's no conductor, so how will the singers know when to sing? The answer is a "click track" in their ears.