The date - circa 1660 - was the tip-off that something unusual was afoot. Lisbon wasn't in the musical vanguard of the burgeoning baroque innovations at that time, but composers such as João Lourenço Rebelo and and Diogo Dias Melgas seemingly wanted to be, creating a hybrid that was clearly rooted in the somewhat impersonal spirituality of the Renaissance while incorporating the sort of individual, chromatic lyricism from which early Italian opera sprang. These 17th-century Portuguese composers reconciled these musical poles so naturally you wonder if they knew just what feats they were accomplishing.

Mass reconstructions can be tedious; this one was not. Because the concert's set pieces (motets, psalms, etc.) are particularly dense, both in their concision and their often astounding harmonic richness, breathing space between them was required. That came in forms from traditional chants to celebratory villancicos. Typically, Piffaro was a model of good musical purpose in an instrumentation that was weighted toward lower brass, though some of the choral sections felt approachably folksy thanks to accompaniment by harp and various guitarlike instruments. Other passages, curiously, had intense instrumental polyphony with minimal vocal participation.

As might be expected from such a generalist chorus as Choral Arts in such specialized repertoire, the singing was that of a group learning to speak a foreign language. Often, you felt the chorus understood what it needed to do to reveal this music to its best advantage but hadn't yet determined how to make the voices operate in a sympathetic, scaled-down fashion. The chorus came through, particularly, in the unaccompanied Salve Regina by Melgas, and overall, left the audience with a positive experience if only because this sort of repertoire is better encountered, at least on first hearing, in a live but somewhat compromised state rather than on a more polished recording. As much as this music rewards cerebral examination, its intensely visceral message still functioned to elevate the public, as opposed to making a wonderful concert (which it does anyway, at least these days).