Most choruses shouldn't even consider singing Bach's six motets in a single concert. The Philadelphia Singers both considered and sang them Saturday at the Kimmel Center for the Performing Arts' Perelman Theater, with no sign of vocal or mental exhaustion.

Yet for the many impressive moments in the program - and gratitude inspired by being able to hear these infrequently heard works sung live - one left convinced of the need for specialists in this repertoire.

That's impractical in this musical community: A chorus the caliber of the Philadelphia Singers can only survive if it also shouts out Carmina Burana and other standard repertoire every few years. Yet the toll exacted by that was particularly apparent in the motets, which are highly architectural constructions built on sacred texts, and are often abstract, personal bordering on obscure and, overall, more difficult to parse than Bach's more familiar works in the choral medium.

On a surface level, my ears wanted less sound and more music. That doesn't necessarily demand fewer singers - there were 24 - but a different kind of vocal production with less vibrato and amplitude. Many, though not all, of the female voices handily accomplished this, though not all the time.

The sheer sound couldn't help obscuring the chorus' good enunciation in moments when it could have been avoided. It also resulted in a step away from comprehensibility.

Music director David Hayes clearly knows these works intimately, and he demonstrated admirable strategy in some of the more thickly scored, double-chorus movements that allow the music to, as they say, "sound." However, even better strategies can come out of a deeper, overall view: If Hayes & Co. had contemplated why a given word was paired with an extravagant welter of notes, there wasn't enough precision in the performances for such insights to be projected.

That one can even ask such elevated questions after a performance is, in itself, a compliment. Aided by a small chamber group of instrumentalists (masochistic choirs attempt this music without that), the singers delivered a performance I'm likely to cherish far more than a decade of Carmina Buranas.

Contact David Patrick Stearns at 215-854-4907 or dstearns@phillynews.com.

The Philadelphia Singers next perform Handel's Messiah Dec. 15 and 16 at the Kimmel Center for the Performing Arts. Information: www.philadelphiasingers.org or 215-893-1999.