In tackling Pier Francesco Cavalli's pastoral comedy, "L'Egisto," the Wolf Trap Opera Company this weekend took on the risks and difficulties of early baroque opera. The result must be accounted a triumph, all the more remarkable for the kinds of challenge involved. With minor exceptions, the singing, acting, staging, design and orchestral performance were all admirably integrated into a production notable for both imagination and finesse.

"L'Egisto" had its premiere in 1643 in Venice. This was the city where the newly emergent art form of opera metamorphosed from an intellectualized entertainment for princes into public show business on a grand scale.

"Claudio Monteverdi, the first great and forever unrivaled master of Venetian opera, died in 1643, and his mantle was next assumed by his gifted, prolific pupil Cavalli.

The conventions, both musical and dramatic, of "L'Egisto" are very different from those which have dominated our operatic listening since the time of Rossini. But the human emotions which animate Cavalli's vain mortals and jealous gods are universal, and there's nothing in the least "primitive" about the way the opera communicates them.

If anything, there is a purity of expression here that makes the 19th-century equivalents seem sickly sentimental by comparison. And at it's height - as in Egisto's lament and mad scene, the final, beatific duet, and the passages for female quartet - the music of "L'Egisto" can stand beside the operatic best of any century.

Raymond Leppard's musical realization, Geoffrey Dunn's translation, John Moriarty's conducting, John Cox' fluid staging and Allen Klein's striking, astrological setting all contributed to the fine net effect. The continuo parts were hard to hear and so was the English text, but the only glaring drawback was James Bowman's hooty, contorted counter-tenor. The other principals, however - David Kuebler, Elizabeth Knighton, Carmen Balthrop, Karen Yarmat and Glenn Cunningham - were splendid, and the singing of the two female quartets was intoxicatingly lovely. In particular, here and in her solos, Sheila Barnes displayed a voice of richly gleaming promise.