As part of its ongoing exploration of musical terra incognita, Hesperus presented an intriguing program, "Christmas in New Spain," Sunday at Meridian House. Functional music for missionaries and their prospective converts is, perhaps, of minimal interest in itself. However, the vocal fireworks of "Por aquel horizonte" were enough for this reviewer to cast her vote for Juan Frances Iribarren as the Mexican Handel.

Issues of greatness aside, these pieces are fascinating documents of peaceful encounters between Europeans and natives. Hark the words of Manuel Joseph de Quiroz's "Clarines Suaves": "Soft tones entwining with harmonies, sound the glory admired today!" -- a translation that itself might translate as "We Spaniards use polyphonic music to shape native culture into one more closely resembling our own!"

The afternoon's selections proved the one-sided nature of musical exchanges in the New World. Save for a garnish of maracas in the 17th-century villancico "Ay Como Flecha," Hesperus came up with little that reflected indigenous influences on European music. But a traditional Peruvian tonadas, blending diatonic harmony with non-European metric shifts, sounded like a predecessor to today's Tex-Mex conjunto music.

Hesperus entrusted all vocal selections to soprano Rosa Lamoreaux, resulting in Mozartean villancicos and tonadas. That's not to say that Lamoreaux or any classically oriented lyric soprano shouldn't sing early music. But adapting to this repertoire requires more than just toning down vibrato (which Lamoreaux did slightly when performing the 17th-century and Indian pieces). It requires thorough understanding of different singing traditions and vocal ideals.

Relegated to predictable lines, harpsichordist Peter Marshall and viol player Tina Chancey played solid continuo. As usual, recorder player Scott Reiss turned up with a virtuoso solo piece. His moment of glory was breezing through the jigsaw-puzzle intricacy of an Inca flute tune.