ORONO – Purists, beware. The ensemble named Ethel doesn’t fit neatly into any categories. In a performance at the Maine Center for the Arts on Sunday afternoon, the New York-based quartet played new additions to the classical repertoire with the exuberant sensibility of a rock band.

Or perhaps one might say the group played cutting-edge rock, jazz and world music on the traditional instruments of a string quartet, albeit with subtle electronic enhancement.

Ethel seems to be a tightly knit group, a real band, with that easy camaraderie which only comes from spending a lot of time together. But in everything from attire to speaking style, the group also seems to be a loose assembly of vital, and very individual, human beings.

Ethel’s members include violinists Cornelius Dufallo and Mary Rowell, cellist Dorothy Lawson and violist Ralph Farris. Sound designer Dave Cook works offstage.

Passing around the microphone, the performers took turns introducing the music and interacting with the audience. Farris, who has family ties to Maine, waved to his mother in the audience and generally charmed all with his quirky personality and bright green socks.

Lawson, dressed in high style and high heels, smiled beatifically through much of the concert. Rowell was a blur of motion, fingers and bow and rock-star hair flying, while Dufallo seemed shy and sincere, lost in the music, happy to let his violin do the talking.

If the members of Ethel are a mixed lot, the music they select is even more so. Like a series of little one-act plays or vignettes, each of these pieces had a different emotional context, and a different musical flavor.

“Pelimanni’s Revenge,” by Finnish composer Timo Alikotila, might have been written in Europe, but it was reminiscent of the sweetly melodic work of American composer and performer Mark O’Connor. Classical music with a country accent is always charming, regardless of the country.

Ethel also proved it could rock, especially in the third movement of John King’s “Lightning Slide,” a semi-improvisational piece that roistered along like a funky and inexplicable Rube Goldberg machine.

“Requiem,” by Lennie Tristano, was like a slow snake up your spine. Other pieces featured Latin rhythms, eerie dissonances, pattering bow percussion like rain on a tin roof, and a boisterous, literally foot-stomping finale performance of “Memory” by Brazilian composer Marcelo Zarvos .

Purists can complain all they care to, but in this reviewer’s opinion Ethel is pure pleasure.

Those interested may find concert schedules, recording information and more at www.ethelcentral.dreamhost.com.