Did a tour bus suddenly let out in front of the Cathedral Basilica of SS. Peter and Paul around the same time as its Friday Christmas concert? No, the line stretching down the windswept block was leading to the first joint concert by Tempesta di Mare, Piffaro, and Choral Arts Philadelphia. No doubt their combined mailing lists helped bring together a large crowd for three weekend concerts, plus an ambitious program titled "Advent Vespers, Dresden 1619."

Because Vespers services tend to be assembled rather than composed from whole cloth, much leeway is possible, allowing the three collaborating ensembles to come up with a varied but stylistically coherent cross-section of music heard at that time and place, mainly Heinrich Schutz, Michael Praetorius, and Samuel Scheidt.

When the concert got down to business with weighty works such as Praetorius' Magnificat and Schutz's settings of Psalms 110 and 128 - going beyond chants and hymns that can tax any concert's pacing - doors opened onto a rich, singular musical world. Schutz drew on any number of gestures (certain kinds of quicksilver rhythm) that originally sprang from the more operatic mind of Monteverdi, with German hymns and chorales as the compositional floor plan. Often in this repertoire, the exterior elements are about formal liturgical functions, but the music transcends that when the inner voices of the vocal writing and the middle sections of the psalm settings slip into more personal expression that tells you how life truly felt in that era.

Antiphonal effects between Piffaro and Tempesta worked particularly well in the acoustical expanse of the Cathedral Basilica. Adding voices to a space with such generous reverberation time created so much sound (even though Choral Arts had just 12 voices - handpicked ones) that the massed ensembles started to cancel out one another. At times, I wondered if I was hearing only 70 percent of the music - disappointing in a repertoire full of fine-cut details.

Periodically, conductor Matthew Glandorf (who also played organ) turned to the audience in an invitation to sing along with the hymns, with music printed in the program. Nice touch, though I felt too distant amid the acoustical expanse to participate. Many of these elements had a chance of correcting themselves in the later performances at venues in Chestnut Hill and Wilmington. I just hope that any disappointment that may have been felt at this concert on Friday won't stop these groups from collaborating again. The blend between Tempesta and Piffaro was special indeed.