Concert programming is an impossible task. It can ruin a good ensemble; and no matter how it is done, it will always offend some listeners. After two Bach Society performances this season, though, I am convinced this group could play anything well. Couple the basic ability of the orchestra with an energetic, sensitive, and brilliant leader--Nils Vigeland--and the result is the kind of exciting performance that delighted several hundreds last Saturday night at Sanders.

"Don't play like the BSO" were Vigeland's instructions to his orchestra before the program. And they did not. Where a certain other Boston ensemble played through Stravnisky last week as though they hated every minute of it, the Bach Society was alive with enthusiasm for Pulcinella. The piece represents the beginning of twentieth-century musical neoclassicism. Borrowing from Pergolesi, Stravinsky fools with the theme throughout, always setting off the expected (as implied by classical harmonies) against his own turn of phrase.

Typical of the tricks played is a passage near the beginning where oboe and double bass are in the usual baroque soprano-to-bass opposition. Suddenly the bass drops away but a listener cannot but help hear the implied harmonies in the highly regular resolution. More lighthearted is the duet between trombone and double bass just before the final trio. The two glissandi in the trombone theme are terribly funny and the audience appreciated it. In general, the orchestral playing was of consistently high calibre, belying the technical difficulties of Pulcinella.

All three singers were at times a trifle overcome by the power of the orchestra, but with such unimportant texts the loss was negligible. The woodwind trio preceding the soprano entrance was beautifully played, as were the string harmonics in accompaniment. No contrast could have been stronger than that of the soprano's aria to the basso's. All three singers sounded best in their first trio: the combined volumes and timbres fitted perfectly with the orchestra. The concert had opened with Glinka's Kamarinskaya, a pleasant diversion which showed off the Orchestra's abilities admirably. The central section of the piece sounds very much like Beethoven symphony extracts, but the similarity ends in a series of pizzicato passages. These were done in perfect synchronization and with great resonance.

The Tchaikovsky Mozartiana that completed the program is an unusual work, most notable in the final Theme and Variations movement. The lighter moments were many: a strings-celeste variation that sounded like bad ballet music, a jazz-like clarinet cadenza, and some frantic runs for the strings leading perfectly to the mock ending. Robert Portney's playing was dazzling in the solo violin variations.

While the Bach Society was a triumph of amateur professionalism, the Graduate Chorale could only be credited with enthusiasm and ambition that together did not add up to the best of performances. The ensemble is extremely fortunate to have had Gerald Moshell as their conductor the past three years. Moshell's imaginative programming allows his group to capitalize on the often unusual nature of the pieces rather than becoming just another chorus singing Handel and Bach.

The Grad Chorale always includes a commissioned work on its programs and always by a composer within the Harvard community. Two of John Stewart's pieces were given premieres last Friday: his Pie Jesu (1965) and The Windhover (1971), a setting of the Gerard Manley Hopkins poem. The latter was by far the better piece. Beginning and ending with female voices only in tone clusters, it calls for seven winds and string bass--all of which were first rate. There is some use of klangfarbenmelodie, the production of a melodic line with varied tone colors, but only with the instruments, not the chorus. The piece owes something to very late Stravinsky, though, and not to Schoenberg or Webern.

Another first for concert performance was the Karl Kohn Madrigal (1966). The accompanist was none other than Nils Vigeland who is an excellent pianist. In addition to the modern music, the Chorale sang two short Monteverdi works and the Bach Cantata No. 131. All three were marred by weak soloists, unable to project and unvarying in tone. Still, it would be foolish as well as unkind to chastise the Grad Chorale for their work; one can only hope that in the future their quality will come up to the level of their enthusiasm.