When the Rowe String Quartet first played here last fall it seemed a group of promise in need of a strong leader. After hearing its concert Saturday night, the second of two given at the Kennedy Center's Terrace Theater, the verdict remains much the same. The quartet has clearly not had time to absorb its new first violinist, Vartan Manoogian, who stepped in only a few months ago. However, the inelegance of his phrasing and his lack of authority raise some doubts about the benefits of such an assimilation.

The evening was generally marked by the kind of erratic performances and stylistic errors that are apt to occur when a group is not of one heart and mind. The program did not come alive until the second trio of the Schumann piano quintet, when pianist Panayis Lyras' forceful approach finally got the ensemble's adrenalin going. An opening Beethoven quartet suffered from both lack of character and Manoogian's intonation problems, apparently due to nervousness. The quartet's vigor and confidence finally came through, in the closing Debussy quartet, alas, when magic, not muscle, was needed.

One suspects that the Rowe Quartet can play much more coherently and consistently than it did this time round. Some moments of warm ensemble blend, especially from the three older members, and violist Pamela Benjamin-Adelstein's consistent musicality point to better days.