"This is the most sophisticated clink in Vienna," boasted comedian and baritone James Billings, gazing in awe at the stained-glass, art nouveau splendor of the jail in the New York City Opera's production of "Die Fledermaus."

Billings was thinly disguised as the opera's drunken jailer, Frosch, but Saturday night at Wolf Trap he let the audience know that he is really an American of the mid-1980s. His jail has "a brand-new Gramm-Rudman coffee machine," he boasted ambivalently. "We don't know if it's going to work."

The coffee machine may be the most elaborately baroque piece of operatic machinery to occupy the Wolf Trap stage since the Metropolitan Opera's oven for "Hansel and Gretel." It might not turn a witch into gingerbread, but it produced what looked like a cup of coffee for the warden (Richard McKee), and it had a speaking tube into which he could bark an order: "Mit Schlag, bitte!" Apparently, the Gramm-Rudman machine didn't work. He never got his whipped cream.

His command was the only German spoken during the City Opera's production of this greatest of Viennese operettas. That fact, plus the topical humor of Billings, may be a key to the slight sense of disorientation left by this superbly staged and sung "Fledermaus." It looked like turn-of-the-century Vienna, but it sometimes sounded like New York. It was a delicious "Fledermaus," but not "mit Schlag."

The difference could be felt as soon as the overture, which was played with precision -- unlike the the way it was done when the Vienna Volksoper visited Washington a few seasons ago. There is a quality that the Viennese call "Schlamperei." You could translate it as "untidiness" or "carelessness," but that is not the Viennese meaning. It is a sort of offhandedness -- a creative imprecision -- that humanizes the music and makes instruments perform like a singing voice.

In Vienna, the violins have to "breathe" as much as the horns or oboes; the musical line will hesitate at the height of a melodic arch. There will be little . . . pauses . . . (called "Luftpausen") at particularly delicious points, like a speaker or singer pacing the words for emphasis, even when the music is wordless.

Hungarian conductors, perhaps even more than native Viennese, seem to have the knack of this kind of phrasing, and one would have expected Imre Pallo (born in Budapest and trained in Vienna) to convey it to his performers. But he has been an American for more than 10 years, and perhaps his music has lost its Central European accent. Or perhaps the New Yorkers in his orchestra (a tough, skilled, versatile group that can do "Carmen" one day and "La Bohe me" the next) resist such foreign encroachments on their style. Whatever the reason, the performance lacked the carefully calculated carelessness that is such an important part of Vienna's proverbial charm. What it needed might be that least New Yorkish of musical qualities -- a sense of relaxation.

Outside of such questions of Viennese musical haute cuisine, the performance was a delight. Sets and costumes were exactly right (except for Rosalinda's party gown, which is often a problem in "Fledermaus" productions). And the singing was of high quality. Young American singers (the City Opera's specialty) may have trouble mastering the specialized body language of Vienna, but they have wonderful voices.

The most wonderful of all, Saturday night, was Claudette Peterson, who stole the show in the role of the maid, Adele.

Her coloratura acrobatics were very impressive (above all in the Act 2 "Laughing Song"), but not more impressive than her ability to articulate and project the words of the English text. Leigh Munro as Rosalinda and Theodore Baerg as her errant but lovable rake of a husband were almost equally impressive in their quite different styles. Michael Cousins carefully walked a stylistic tightrope in the role of the Italian tenor Alfredo (in some ways, the hardest bit of characterization in the show), and William Parcher was properly enigmatic as Falke, the contriver of the whole charmingly silly stage action.

This performance exemplified a trend seen in several "Fledermaus" productions of recent years: the use of a tenor rather than a mezzo in the epicene role of Prince Orlofsky. In casting a woman for a male part, Johann Strauss was paying a graceful tribute to Mozart and unknowingly anticipating the greatest work of a later, unrelated Strauss: Richard. As a part of the performance tradition, one wants to insist on a woman in this trouser role, but it is hard to be a purist on this point when Orlofsky is performed by a tenor as adept as Douglas Perry, who outsang and outacted most mezzo Orlofskys I have seen.

As always, when the City Opera does "Fledermaus," Perry got a laugh with a line from his "Chacun a' son gou t" number: "I do not care for humorists, not even Johann Strauss./ The opera that I hate most is called 'Die Fledermaus.' " But this does not fairly represent the City Opera's attitude. The company does not hate "Fledermaus" (that would be like hating money in the bank); it simply insists on doing the music its own way.

That way included a bit of dancing (not required by Strauss, but allowed for a gala atmosphere) during the party scene. Ballerina Patricia McBride was exquisite and Spanish dancer Esperanza Galan was properly fiery in their solo numbers, but there was a bit of culture shock when they performed together.

McBride's routine was nicely suited to the music, but Galan did the first (and, I trust, the last) bit of Spanish dancing I have ever seen to the music of the "Trisch-Trasch Polka."

As Orlofsky might have said, "Only in America."