SKANEATELES - If you combine two violins, a viola and a cello, the resulting ensemble will comprise a traditional string quartet.

Now have the musicians perform progressive jazz tunes by the likes of John Coltrane and Herbie Hancock. Those who believe the unlikely amalgamation would never work have never heard the Turtle Island Quartet.

The unique Grammy-winning ensemble was the featured act at Friday afternoon's Skaneateles Festival concert, held at the Austin Park pavilion. The free community performance, which was attended by about 100 guests, was part of the festival's “All That Jazz” theme for the first week of the month-long concert series, now in its 29th year.

“They played at the festival about three years ago, and we're delighted to have them back again,” David Ying, SkanFest co-artistic director, said prior to the concert.

Just before the performance began, quartet member David Balakrishnan, who plays the violin, discussed the group's unique sound.

“We're a classically trained string quartet, but we all share a sort of jazz mentality,” he said. “Were not like a lot of traditional string quartets in that we play what we want to play while we're up on the stand.”

Earlier this year, the ensemble won its second Grammy award in the Best Classical Crossover Album category for “A Love Supreme: The Legacy of John Coltrane.”

“The idea for the album was to come up with songs for a magnum opus that no one would ever expect from a string quartet,” Balakrishnan explained.

“Unexpected” was indeed the theme for the day. Though the concert was originally scheduled to be held in Clift Park in downtown Skaneateles, organizers moved the performance to the pavilion on Jordan Street because of Friday's steady rain.

“I have to say, this is the first time we've ever played in a hockey rink,” violist Jeremy Kittel quipped when the quartet took the stage, drawing a laugh from the crowd.

From the first notes of the group's opener, Coltrane's “Moment's Notice,” the ensemble, which in addition to Balakrishnan and Kittel included violinist Mads Tolling and cellist Mark Summer, demonstrated why they've won two Grammys.

For about an hour, the Turtle Island Quartet swung its way through tunes by Coltrane, Hancock and Miles Davis, in addition to original songs written by ensemble members.

The quartet has a knack for interpreting jazz progressions and improvised melodies with a somewhat “classical” feeling. Cellist Summer alternated between using a bow and plucking his instrument's strings much like an upright bass.

Similarly, the other three players sometimes struck their instruments' strings with their bows to create a percussion line for the particular tune.

“I've always thought these guys were incredible musicians #- and now I'm glad the rest of the world has caught up with me,” Ying said.