Maurice Sendak, who acquired an international reputation as a writer and illustrator of children's books, has also become known in the last few years for his operatic work. In Washington, he made a hit several years ago with his sets and costumes for Mozart's "The Magic Flute," originally created for the Houston Grand Opera, which were rented for a memorable production by the Washington Opera.

Sendak's affection for Mozart is shown on several levels in his "Magic Flute" sets and costumes, which contrast the two conflicting worlds of the opera: the Age of Enlightenment in the court of Sarastro and his colleagues; ignorance and superstition in the Queen of the Night and her crew. But the incidental monsters in the show are most congenial to his familiar style; being by Sendak, they are more cuddly than most monsters seen on operatic stages. They will be back in town Thursday night for a new "Magic Flute" at Wolf Trap, sung by the highly talented and superbly trained young singers of the Wolf Trap Opera Company.

Meanwhile, Sendak has been busy with other operatic projects, including productions of Janacek's "The Cunning Little Vixen" (telecast on PBS in a performance by the New York City Opera) and Prokofiev's "Love for Three Oranges" (commissioned by the BBC for the Glyndebourne Festival). And in recent years he has become a cocreator of operas with British composer Oliver Knussen. He has finished the designs and libretto for his second opera, based on his book "Higglety Pigglety Pop" His first opera, "Where the Wild Things Are," still awaits its first American staged production (scheduled by the Minnesota Opera for Sept. 27), but it has had staged productions in Belgium and England and a concert performance in New York. Now, it can be heard in a recording (Arabesque 6535-L, one LP with libretto) based on last year's English production.

When a book is translated into opera, it is usually simplified and intensified. In this case, since the source is a picture book, the operatic treatment actually makes the subject more complex -- or makes explicit some of the complexities only implied in the original. Knussen's music definitely intensifies the story; it supplies vivid musical substitutes (if not equivalents) for the pictures in the original, and the result is a "Wild Things" that is wilder than ever -- a study of childhood, its insecurities, frustrations and fantasies with (as the libretto says) "a contained violence that could at any moment get out of control."

The musical idioms are eclectic, inspired by sources as diverse as "The Rite of Spring," which is echoed in the "Wild Rumpus" scene, and "Boris Godunov," which is wittily quoted during the coronation of Max, the hero, by the Wild Things. A substantial part of the score is orchestral, to accompany miming, dancing and spectacular scenic transformations, and the orchestration is brilliant.

There is a small mezzo role for Max's mother, but vocally the opera depends mostly on the soprano in the title role, who should also be an acting virtuoso to portray an unruly preschool child. Rosemary Hardy sings splendidly (though the libretto is needed to make out all the words) and projects the rages, fantasies and infantile megalomania of little Max convincingly. The Wild Things, a five-part chamber chorus, have to produce a bit of singing (in barbershop harmony) and a lot of grunting, muttering and random animal noises. They do it zestily in this production, and composer Knussen, leading the London Sinfonietta, demonstrates that he is also a fine conductor.

Stravinsky's "The Rake's Progress" is another opera inspired by a series of pictures: Hogarth's cycle of paintings (and, later, engravings) produced under the same title 250 years ago. Unlike "Where the Wild Things Are," it is available in a first-class video recording (Video Arts International, VHS or BETA VAI 12), but for audiophiles who are not videophiles the London recording under Riccardo Chailly (London 411 644-1, 3 LPs with libretto) can be warmly recommended.

The conducting is considerably more expert and vivid than in the two recordings under the composer's baton, though Chailly sometimes overexerts his singers, much as Toscanini used to do. The finest performance is that of Samuel Ramey, who by now owns the role of Nick Shadow, and the secondary roles of Baba and Sellem are in the hands of two highly capable specialists, Sarah Walker and John Dobson. Occasional signs of strain can be heard in the voices of Philip Langridge (as Tom Rakewell) and Cathryn Pope (Anne Trulove), but their general standard of singing is high and the performance is thoroughly enjoyable.

For those with video equipment, the VAI tape may be preferable; the musical standards are on a comparably high level, and the visual impact reinforces that of the sound, which is good but monophonic and not up to the standards of London's digital stereo.

Other current operatic recordings worthy of note:

*Gottfried von Einem: Dantons Tod ("Danton's Death"). Theo Adam, Werner Hollweg, Horst Hiestermann, Krisztina Laki; Austrian Radio Chorus and Symphony Orchestra, Lothar Zagrosek (Orfeo S 102-842 H, two LPs with libretto). The trial and execution of Georges Danton are the climactic episodes but by no means the only points of interest in this tensely dramatic, fast-moving opera, which presents a vivid view of the French Revolution. Von Einem has a sure sense of dramatic values and pace, and he infuses his score with some splendidly Viennese touches of gallows humor to balance its moments of stark drama. The libretto is taken from Georg Bu chner (1813-37), that curiously modern playwright who also provided the libretto for "Wozzeck." "Dantons Tod" may not have quite the historical stature of Alban Berg's masterpiece, but it is a superbly crafted piece of musical theater and it is well represented in this 1983 performance from the Salzburg Festival, where it had its world premiere in 1947.

*Purcell: King Arthur. Gillian Fisher, Elisabeth Priday, Ashley Stafford, Paul Elliott, Stephen Varcoe; Monteverdi Choir and English Baroque Soloists, John Eliot Gardiner (Erato NUM 751272, two LPs with libretto). Purcell's "King Arthur" is not really an opera but very elaborate incidental music to a play. Its 40-odd numbers, ranging from a pagan sacrificial rite to a drinking song, also include pastoral episodes, war music, love songs and monologues by various pagan deities. They have little connection to one another or to a coherent plot, but this hodgepodge includes some of baroque music's finest moments. The performance (on original instruments and baroque-trained voices) is well styled.

*Albinoni: Il Nascimento dell'Aurora. June Anderson, Maragarita Zimmermann, Susanne Klare, Sandra Browne, Yoshihisa Yamaj; I Solisti Veneti, Claudio Scimone (Erato NUM 751522, 2 LPs with libretto). This is not an opera but a sort of pageant composed to celebrate the birth of an unidentified royal personage (possibly the Empress Maria Theresa) in Vienna. Albinoni, best known for his Adagio for strings and a few trumpet concertos, turns out to be also an adept vocal composer. The material offers little except pretexts for spectacular singing, but there is plenty of that from the cast of relatively unknown young performers.

*Monteverdi: Orfeo. Nigel Rogers, Patrizia Kwella, Emma Kirkby, Jennifer Smith; Chiaroscuro, Nigel Rogers (Angel/Reflexe 4D2X-3964, two cassettes with libretto). Dating from 1607, this is Monteverdi's first opera and nearly the first ever composed. Its interest is largely historical compared to his final opera, "The Coronation of Poppea," but Monteverdi's music has, as always, a special grace and vitality. The performance is excellent.