The delightful partnership between flutist Carol Wincene and guitarist Eliot Fisk at the Library of Congress yesterday evening showed little evidence of the fact that Fisk was a last-minute replacement. Canadian guitarist Liona Boyd, who was scheduled to appear with Wincenc, suddenly became indisposed yesterday and Fisk rushed in at noon from New York to take her place. More than skillfully filling the gap. Fisk entered into lively exchanges with Wincenc that reflected a remarkable unanimity of spirit.

In addition to an abundant technicaly ability, both possess fine musical instincts. Wincenc has a winning way with a musical line, imparting a vitality that seems spontaneous. She rushes into passages with a delicate impetuosity, sometimes teetering into small difficulties with tone quality and control, yet consistently engaging the listener's interest. Her mercurial talents proved ideal for the rapidly shifting moods of Hindemith's set of Eight Pieces for solo flute and the dramatic changes of Varese's "Density 21.5."

In his solo selections, Fish exhibited an equally individual approach, handling the many demands of Bach and Villa-Lobos with easy artistry, producing lovely legato lines and a sensitively varied touch. For his exceptionally amiable contributions to the dual works, particularly in a Giuliani sonata, he received a well-deserved kiss on the cheek from Wincenc at the program's end.