Southorn returned in the second half as the violin soloist in Uzbek composer Dmitri Yanov-Yanovsky’s 1997 Lux aeterna, for violin and 14 players. The solo part, rich in glissandi and double-stopping, moves over and through an intricate, often frenetic instrumental texture. Southorn’s account of the solo line was eloquent and admirably secure, seeming to bring the wildly varied elements of the surrounding music into focus around it.

Three songs from Gavin Bryars’s Adnan Songbook of 1996 followed the Milhaud on the first half. They proved to be extremely economical in conception: direct, unforced vocal settings of Lebanese poet Etel Adnan’s terse texts, sparsely accompanied and harmonized with great simplicity. The dusky instrumental ensemble — two violas, cello, bass, bass clarinet (doubling clarinet), and acoustic guitar — did little more than discreetly underlie Brittany Hicks’s cool, clear soprano.

The music was oddly haunting but disturbingly insubstantial, with little for the ear to take hold of, beyond the harmonious timbres and the slightly abstracted emotional tone. It made this listener curious to know what the remainder of the cycle is like. The three songs given Saturday all come from the second half of the set. The first (which, among other things, uses electric rather than acoustic guitar) may contain a wider range of moods.

BluePrint’s entire 2006-2007 season is liberally sprinkled with world premiere performances of commissioned works, and Saturday night brought two of them. Bruce Mather’s Music for San Francisco, for oboe, horn, harp, piano, violin, viola, and cello, received its first performance from Ensemble Parallèle under Paiement’s direction. The work, an outgrowth of an earlier piece for oboe and harp, is much concerned with the possibilities of quarter-tones. The harp is so tuned as to be able to play familiar triads with one pitch of each shifted downward by a quarter-tone, and these collections become the basis for the bulk of the piece’s harmonic language.

The melodic lines, too, are quarter-tone-obsessed, returning again and again to an oscillation between one pitch and another a quarter-tone up or down from it. This is the main material of the piece, interrupted at intervals by a much faster, skittering, quarter-tone-free music led by the piano. Despite the obvious care with which the players (not only the strings, but oboe and horn, as well) gave to tuning the microtonal increments, the effect still seemed a little queasy, the sense of unease not being helped by the music’s ambiguous trajectory. The piece seemed to explore its chosen territory lovingly but narrowly, and to return on itself repeatedly, to mysterious purpose. It was most interesting, yet puzzling.

Jacques Desjardins writes that his Volupté, whose concert-ending premiere gave its title to the entire program, is about the layers of sensory experience and the mind’s contemplation of these layers. Certainly there was plenty of immediate sensory experience to be enjoyed. Desjardins allowed himself a colorful ensemble (piano, percussion, and small groups of strings, woodwind, and brass, including a prominent tenor sax), and made the most of it.

Often the various instrumental choirs were played off one another in abrupt rhythmic-unison lines that sent the aural interest veering moment-to-moment from one choir to the next. Striking, rhapsodic solos emerged periodically from the heady density of the texture. (One especially eloquent quasicadenza for the bassoon earned its player a justifiable solo bow; I do not, unfortunately, know which of the evening’s two bassoonists to credit.) The whole was vivid, alive, and clearly fun to play.

One of the outstanding features of BluePrint since its inception has been the steady stream of pieces for such large, colorful ensembles as these — pieces that, for logistical reasons, are unlikely to be often performed outside of such a series. I hope that Nicole Paiement will consider returning to some of these works in future years, especially those written for the BluePrint Project. She and her ensembles are on their way to assembling a fine, impressively varied repertory.