Either way, a successful piece sparks imitation, leading to both a fresh repertory and new groups to execute it. Those ensembles then compel the creation of more custom-tailored music.

Presumably that explains how the Electrum Duo the relatively unorthodox pairing of a flutist, Sophia Anastasia, and a percussionist, Ralph Sorrentino was able to fill the two-hour program at Bargemusic on Friday night. Appearing as part of the praiseworthy Here and Now series devoted to contemporary American music, they covered an impressive range of styles in 10 works composed since 1960.

Ms. Anastasia, speaking from the stage, introduced Ingolf Dahls Duettino Concertante, from 1966, as the mother of all flute-and-percussion pieces. Dahl, an inventive composer born in Hamburg of Swedish-German parentage, became a tireless force for contemporary music after settling in Los Angeles in 1938. He was not the first to pair flute and percussion. One earlier example, Leon Steins Introduction and Rondo from 1960 opened the concert.

What Dahl came up with, though, was a compelling premise. His piece challenges the flutist to play with a percussionists rhythmic verve, while calling on the percussionist to evoke a flutists airy melodic lines. The Electrum players were persuasive advocates: Ms. Anastasia played with brightness and vigor, while Mr. Sorrentino pattered across drums, cymbals and woodblocks with an impressive feeling of flow. The playing had an air of conversational spontaneity; each performer seemed to finish the others statements now and then.

The best works on the program echoed the creative equanimity that Dahl had devised. John Heiss even quoted Dahls work in his crafty Epigrams. George Frocks irresistible Nimrod/Kimbob crunched themes from Elgars Enigma Variations into a playful six-minute romp. Rumbling drums and pealing crotales conjured a ritualistic air in David Trums Unfamiliar Shores, with Ms. Anastasia sometimes serving as second percussionist.

Mostly called on for lyricism elsewhere, Ms. Anastasia dug into the brusque hisses, sputters and growls of Joseph Pereiras earthy Echi Dromi with gusto. Her vitality was neatly balanced by the graceful efficiency with which Mr. Sorrentino choreographed his manifold tasks throughout the evening. Perhaps it was an ability to play against type that made these players cohere so effectively.