Listeners embarking on the Utah Symphony's three-day Mozart Festival were served the most substantial course of all in Friday night's opening concert. Leading from strength, the orchestra and Utah Symphony Chorus put their authoritative stamp on a wonderful performance of Mozart's Great Mass in C minor, K. 427, in which all elements worked together to richly interpret this monumental work, all too seldom performed here.

As with his Requiem Mass, Mozart left the Great Mass incomplete, and movements from other masses were customarily used to fill in. The version "reconstructed and completed" by Helmut Eder from the composer's manuscripts received its U.S. premiere at this concert, and it did indeed have the ring of authenticity.In this mass, Mozart spoke with blazing grandeur and supreme dignity, and always with the joyous confidence that marked the temperament of one who spent little time reveling in the more fearful and ominous aspects of the mass, but went beyond to glorify its praise and hope of salvation.

Ensembles are frequently massive, using many parts and even double chorus, and often calling for extended resources. The singers, trained by Ed Thompson and Bonnie Winterton, was not found wanting. They put forth a declamatory Kyrie of confident tone, a radiant Gloria and a splendid Qui tollis, whose grand magnitude still made room for a softly pliant miserere.

The Credo rolled forth confidently, the Sanctus had a grand expensive effect, and the singers cleanly encompassed the fugal floridity of Hosanna in excelsis, ending in a blaze of glory. Indeed, one happy surprise and grand reassurance followed another in this good interpretation.

Utah soloists, led by JoAnn Ottley, did themselves proud in this difficult music. One may be glad that Mozart loved a soprano, for many of his happiest inspirations came for that voice, and the Great Mass has more than its share.

Ottley was in superb form for an Et Incarnatus of great serenity, ideally paced and clearly delineated, marked by virtuosic wide upward skips to pianissimo landings.

Julie Reynolds distinguished herself in the joyous Laudamus te, showing a full, brilliant voice equal to symphonic demands. Terrence McCombs joined the women for a splendid Quoniam tu solus sanctus - a full-out virtuosic display that found all three in good balance and in command of the difficult rhythms and flights of this showpiece.

Preceding the Great Mass, all must be considered prelude, though an enjoyable prelude well performed. The Divertimento for Strings in D major, K. 136, shone forth as a bright and sunny work of simple form and structure, well calculated to put an audience in tune. Ottley sang the youthful Mozart's "Exultate, Jubilate" appealingly, especially a sparkling "Alleluiah." And the beloved "Ave verum corpus" introduced a little of the choral majesty that was to come.