The group known as Chapter 6 would never be characterized as sartorially elegant. Perhaps informal or even “shabby-chic” would better serve. But the artistry of these six singers was anything but your everyday slice-of-life. This professional a cappella ensemble opened the season’s Center Stage series to a large and enthusiastic Stewart Theatre audience at North Carolina State University.

Extreme eclecticism might describe the musical repertory. It could be argued that anything anyone has ever played or sung is fair game to be morphed into one of their arrangements. Opening were “What a Wonderful World” and “Don’t You Worry ‘Bout a Thing.” Theme and Variations seemed to be a specialty. They applied multiple musical genres to a signature piece, “It Don’t Mean a Thing If It Ain’t Got That Swing.”

By the time they had launched into the third or fourth offering, you suddenly thought, wait a minute. Isn’t this group supposed to be strictly a cappella? Whence comes that  accompaniment? You then gradually realized that these rather distinct percussion and bass sounds were being created orally by those imaginative singers. It was at times a bit startling to note how realistic some of that “accompaniment” sounded.

“Ode To Krispy Kreme” came about when, during their touring, they realized that two of the members had never sampled one of those nutritional necessities (especially the glazed variety). About midway in the program they conducted a mock audience quiz, awarding a Chapter 6 compact disk to each of the two “winners.” Cutting the quiz short, the emcee explained that the two disks were all they could afford to give away.

The ensemble started as students at Millikin University in Decatur, Illinois, winning their first competition in 2000, and “turning pro” in 2002. There seems to be no “star” performer. Each member takes his turn as soloist and speaker from time to time. During the performance of a given number, it is virtually impossible to tell who is doing what in providing the versatile sound effects.

A couple of pieces could lay claim to magnum opus status for the evening. “The Wizard of Oz” was offered as a six-minute condensation of the famed movie. The story was humorously recounted along with such stalwarts as “Yellow Brick Road,” “Somewhere Over the Rainbow,” and “We’re Off to See the Wizard.” Each main character was depicted in some fashion. Then there was “Rhapsody in Blue.” Here came an actual departure from a cappella form. A piano was wheeled onto the stage for the seventh member of the group, Mark Grizzard, who is composer, arranger, sometime singer, and pianist. In this condensation they reportedly “removed the difficult parts.” Gershwin would have been blown away to hear his great work adapted for an accomplished pianist, with six creative vocalists constituting the “orchestra.”

The program brochure pointed out that “these young men stand ready to sing for anyone who’s ready to smile.” It seemed that every audience member was indeed ready.