Not even so sure-footed a Mozartean as Donald Gramm can take 11 relatively inexperienced singers and plumb the musical and dramatic depths of "The Marriage of Figaro."

So, in the new production at Wolf Trap, with which the singer made his debut as a stage director last night, Gramm goes on a different, and sometimes delightful, tangent. He recognizes the potential risks of working with singers who may be singing the parts, or even Mozart, for the first time and of doing one of the most subtly nuanced of operas in the outdoors. Instead of emphasizing the profound, he goes after the fun, and in the process comes up with some engaging staging ideas.

The emphasis is on the broad comedy side of "Figaro," but not once did Gramm's inventions seem coarse; vulgarity of any kind in Mozart would be disastrous.

Gramm ended each of the four acts with a surprise comic bang that kept the momentum high. Perhaps the boldest of his production numbers came first. This is Figaro's mock celebration of the military glories that the kid Cherubino will experience as a result of the count's banishing him from the Almaviva Court, "Non piu andrai."

Normally the chorus would have long since left the stage, but Gramm keeps them on. As the aria grows, instead of having Figaro start to exit with Cherubino to the tune of the march alone, the whole chorus puts Cherubino back into the same chair behind which and in which he has been hiding through much of the act. They lift the chair plus Cherubino to shoulder height and all march out to the tune of the march. It's show biz, and it's good show biz.

Likewise, at the end of the third act, after the double weddings of Figaro and Susanna and Bartolo and Marcellina, Gramm emphasizes the revolutionary political theme of the work by having the servant Figaro dance over to the count's throne, where he sits and pulls Susanna onto his lap as the curtain goes down.

Gramm's action occurs within grand sets, with lavish costumes borrowed from the New York City Opera.

Which brings us to the music. Last night's performance was cast from the 20 members of the Wolf Trap Company, a group of relative novices brought here for the season as summer interns. These are mostly people whose teaching is over and who are now trying to launch careers. Tomorrow night it will be repeated with other interns.

These performers showed varying degrees of promise. And in one case the singing, and especially the acting, showed something more than promise.

Patricia Schuman was a charming Cherubino. She looked as much like a young boy in the role as anyone I have ever seen. There was an incredulity with which she reacted to things with her wide-open eyes and her pinched nose that seemed genuinely adolescent. The singing was impeccable, vocally and stylistically.

In this opera of male and female couples, the ones at the top, the count and the countess, came off least well. Richard Davis simply doesn't have the voice for the count and Jennifer Barron robbed the countess of her great dignity. The countess can't giggle and grimace and gesticulate like that. Figaro (Bruce Kramer) and Susanna (Virginia Boomer) had the right kinds of voices and handled the music with ease, though neither had a particularly pointed characterization yet. Marcellina (Diane Kesling) and Bartolo (Robert Ferrier) were fine comics, thought Ferrier's voice seemed weak in the first act. Richard Woitach of the Metropolitan was the conductor.