In a Duke Performances program filled with choral transcriptions of instrumental works (only three of eleven pieces were heard as originally composed), the Latvian Radio Choir showcased vocal dexterity and superb stability of pitch. Although ranging in musical styles from the late Renaissance/early Baroque works of Giovanni Gabrieli and Carlo Gesualdo to music of our own time, the choir’s tonal palette seemed uniformly tailored to the Romanticism of Gustav Mahler.

The program: “Deus in Nomine Tuo,” Giovanni Gabrieli; “Ich bin der Welt abhanden gekommen” and “Die zwei blaue Augen,” Gustav Mahler, arr. Clytus Gottwald; “Nunc Dimittis,” Arvo Pärt; “Mūsu Māšu Vārdi” (Our Mother’s Names), Pēteris Vasks; “Hear My Prayer, O Lord,” Henry Purcell/Sven-David Sandström; “Otche Nash,” “Bogoroditse Devo,” and “Veruju” (Pater Noster, Ave Maria, and Credo), Igor Stravinsky; “Louange à L’éternité de Jésus,” Olivier Messiaen, arr. Gottwald; Tres Sacrae Cantiones, Carlo Gesualdo di Venosa, completed by Stravinsky; “Kein Deutscher Himmel,” Gustav Mahler (the Adagietto from Symphony 5), arr. Gérard Pesson; Jubilemus Singuli, G. Gabrieli.

Under Artistic Director/Conductor Sigvards Kļava, the 24 singers, equally divided between soprano/alto singers and tenor/bass singers, were encouraged to make their own individual vocal contributions to the ensemble, rather than to make a choral “blend” a primary goal. This was most evident in one soprano voice, which on several occasions produced an edgy, strident tone in its highest register. The group’s best sound was in its most quiet passages, particularly in their performance of Mahler’s Fifth Symphony Adagietto and the pianissimo sections of Pärt’s “Nunc Dimittis.” Klava’s baton-less conducting (the fingers of each hand usually parted) was never histrionic, but clear and expressive.

While all the vocal parts were there, the program’s opening and closing Gabrieli works were the least effective works of the evening because they lacked the instrumental parts doubling the voices, thus contributing to the “everything sounded tonally similar” problem. Also, the choir’s Latin diction was simply not good, even allowing for the resonant Duke Chapel acoustic. Gabrieli wrote over eighty motets, many for eight or more voices/instruments; while it is possible to sing them a cappella, just as J.S. Bach’s motets may be sung without their intended instrumental support, such unaccompanied performances omit an element of intended musical color.

The two Mahler Lieder, originally composed for voice and piano or voice and orchestra, were heard in fascinating choral transcriptions by Clytus Gottwald. Mahler’s rich harmonies were effectively transferred into the choral medium, as was also the case in Pesson’s transcription of Mahler’s Adagietto, perhaps the evening’s most vocally-luxuriant performance. The quintessentially-Mahlerian harmonies seemed just as moving in their choral guise as they do in their original form, as beautifully sung by the Latvian ensemble.

Pärt’s “Nunc Dimittis” was sensitively performed, its triadic “tintinabulations” moving through the warm acoustic as if melding with it in an exquisite reading of which the composer would have been proud. The first half of the concert concluded with Latvian composer Vask’s atmospheric setting of a poem by Märis Čaklais which, despite its title, is about birds. The singers’ voices at the work’s close are ornamented by multiple sounds of bird calls, whistled by members of the chorus.

Swedish composer Sven-David Sandström’s (not “Jan” Sandström, as stated in the program and one of the program notes) treatment of Purcell’s anthem “Hear My Prayer, O Lord,” is not a transcription, but rather a transmogrification, as Purcell’s music, with its own 17th century dissonances, dissolves into a series of lamentations depicting the word “crying” from the text “… and let my crying come unto thee.” Unlike Purcell’s minor-chord ending, Sandström brings the work to a close with a serene C major chord, undergirded by the bass section’s low C.

Three homophonic pieces by Stravinsky, inspired by the Russian Orthodox liturgy, followed, sensitively sung in their original Slavonic (Latin versions are also published). These would surprise anyone who thinks of Stravinsky only in terms of his “modern” musical language; they are simple liturgical settings, their rhythms determined by their texts, with traditional harmonies. Less traditional harmonies returned with another Gottwald transcription, this time of the fifth “Jubilemus” movement, originally for ‘cello and piano, of Messiaen’s Quatour pour le fin du temps (Quartet for the end of time). The extremely slow tempo of this choral version of “Louange à L’éternité de Jésus” (“Praise to the eternity of Jesus”) lends itself to a reverberant acoustic; it was warmly sung and warmly received.

More Stravinsky followed, but this time as one composer completing the unfinished works of another: Three Sacred Songs by Carlo Gesualdo (1560-1613), Prince of Venosa and celebrated composer (and murderer, but that’s another story). Gesualdo’s harmonies were often so forward-looking that if more composers had followed his lead, musical language would have reached the 12-tone systems of Schoenberg and Berg at least a century earlier. It was only natural, then, that Gesualdo’s music was intriguing to Stravinsky, who decided to complete three works left unfinished by the earlier composer. It was good to hear these six- and seven-voiced motets, which are infrequently performed because of their difficulty. Again, the Choir sang them beautifully, even if it was difficult to know in what language (Latin) they were singing.

The program closed with the Mahler Adagietto and another Gabrieli motet, Jubilemus Singuli. The audience demanded an encore, and the singers responded with a delightfully-light work which I assumed to be a Latvian folk-song. Regardless of its genre, it was a welcome conclusion to a fascinating program.

The printed program suffered from disorganization (there was the program order, then program notes, then texts/translations, rather than grouping all things pertaining to one composition together) and from considerable errata, beginning with the group’s name, in large capital letters, as the “LATIVIAN” Radio Choir. There were omitted letters, one work’s title was totally wrong, one composer’s given name misidentified, and the Purcell anthem text was not the one sung, but that of an entirely unrelated anthem. Regardless of the source of these errors, they should have been corrected before going to press.

In sum, a fascinating program of mostly transcribed works, rich in invention, well-sung, but lacking variety of tone and clear diction.