Nothing in recent memory has exposed the acoustic deficiencies at Sunset Center theater more clearly than the first two concerts of this summer''s Carmel Bach Festival.

On Saturday night, the festival chorale, deployed outside the proscenium, filled the auditorium with a vivid, three-dimensional presence. But on Sunday afternoon, the larger chorale/chorus combination, situated behind the orchestra (and the proscenium) might as well have been in the next room. In terms of stereo imaging, there was no discernible left-to-right separation and no depth. Moreover, there appeared virtually no difference in loudness, only in clarity, whether they sang softly or at full throttle.

In fact, Sunday''s most cleanly etched choral singing occurred during the quiet passages--notably the often-overlooked Qui tollis in the Gloria, and the weirdly dissonant Et expecto resurrectionem in the closing moments of the Credo--of JS Bach''s celebrated Mass in B Minor. Here, the choral display was radiantly textured and deeply expressive. (The choral work in the well-known Crucifixus might have made a similar impression but for a decision to play the accompanying string staccatoes as a foreground martel‚, suggesting a hammer driving nails through the hands and feet of the crucified Jesus.) Among the familiar soloists was a new voice, soprano Kendra Colton, sporting evident coloratura agility with tightly focused, slightly nasal tone. Hornist Glen Swarts gracefully negotiated the challenges of Quoniam tu solus sanctus.

The

choral intensity missing from Sunday''s performance had been amply evident on Saturday. Not surprisingly, the orchestral and solo work took their proper balance as well. Pealing with trumpets and drums, Bach''s cantata O ewiges feuer, set a festive stamp on opening night. Soloists Catherine Robbin and Sanford Sylvan were joined by newcomer, tenor Alan Bennett, a shiny, bright replacement for the retiring David Gordon (now the festival''s vocal coordinator and Adams Master Class director), but with a narrower tone. Sparked by the assertive leadership of concertmaster Elizabeth Wallfisch, Elgar''s melodically rich Introduction and Allegro for strings, a concerto grosso modeled on Handel, banished any doubts as to the capabilities of the festival''s string ensemble. Baritone Sylvan took unequivocal ownership of Bach''s cantata Ich habe genug, especially in the second aria, Schlummert ein, which was performed sotto voce with muted strings, the very dream-state suggested by the text. Oboist Roger Cole also showed exceptional musicality.

The program''s closing work, the "dramma per musica" Vereinigte Zwietracht, a cantata evidently commissioned to celebrate the installation of a new law professor at Leipzig University in 1726, finds Bach struggling with a style he doesn''t trust. The homophonic writing for chorus rubs on the composer''s polyphonic fur, and he seems to retaliate with recitatives and arias even more ungrateful--to hear as well as sing--than usual. (It is hard to imagine that Bach wouldn''t have chosen to destroy the piece after its occasion, but in fact, he reworked it for another non-religious ceremony, giving it a different text.) One may applaud the festival''s effort, but the piece is barely worth it.

The Monterey County Symphony--now renamed Monterey Symphony--has engaged a former Mozart in Monterey Festival violinist as its concertmaster for the 1998-99 season. William Barbini, for 12 years a member of the New York Philharmonic, was concertmaster and soloist with the Sacramento Symphony until that orchestra folded two years ago. His role in Monterey will be especially crucial as the orchestra will have no music director during the coming "search" season.

Quiz of July 9: What winner of the Prix de Rome wrote a symphony subtitled "City of Rome?" Answer: Georges Bizet.

This Week''s Quiz: To fool his usually caustic critics, what major French composer successfully introduced his own "Chorus of Shepherds" under the pseudonym Pierre Ducr‚?