Like any enterprising vocal group, Choral Arts Philadelphia has faced many mid-performance dangers at the hands of J.S. Bach over the years, but its Sunday performance of the supremely challenging

Mass in B Minor

was admirably solid, with subtle provocations.

The grand finale of the Bach Festival of Philadelphia, the performance, at the First Baptist Church had a strong conceptual foundation: Music director Matthew Glandorf embraces the historically informed performance camp, even using authentic pronunciation that gives the music a distinctive tint.

But the main benefit of having such a strong, encompassing overview is that the weak links - and Mass in B Minor performances always have them - are carried by the sweep of firmly founded performance decisions.

The drawback is that even seasoned singers must express themselves within less-expansive boundaries: Here, the music's attacks were clean and releases even cleaner, evidence of a fundamental philosophical difference that runs against any modern performer's natural inclination to "sell" the music. The idea is that the words and notes contain all the necessary power, especially if the listeners (as in Bach's time) needed no convincing on the subject of religious truths.

The effect, even under such experts as the late Gustav Leonhardt, can seem awfully sober. On Sunday, some of the vocal soloists seemed inhibited at times. But only at times. Mostly, Bach's voice emerged with exceptional clarity, with an accent that took some getting used to ("Credo" came out "cree-do" rather than "cray-do"). Also, usually serpentine contrapuntal lines were parceled into smaller gestures that reminded you this music is far more than brilliant solutions to technical challenges.

Regardless of all that, sopranos Clara Rottsolk and Laura Heimes had an exhilarating vocal blend in the "Christe eleison." Tenor Philip Anderson and Brian Ming-Chu were nearly ideal. Only countertenor Bryan deSilva was not having a good day.

The 50-member chorus had a demure, low-vibrato sound, more successful in female voices; when the inner counterpoint grew muddy, male voices were often the problem.

While even the best period brass players have audible struggles, this orchestra had fewer than usual in a fine lineup that included Tempesta di Mare's Gwyn Roberts on winds and faces I've seen at New York early-music events. Sometimes, that's what's necessary for Bach's greatest masterpiece.