Concertgoers the world over have heard the Kurtz brothers—but rarely together. Conductor Efrem, 51, has always shied away from family favoritism in picking his soloists. Cellist Edmund, 43, a front-rank virtuoso, has always agreed, but he adds, "Brothers can come together occasionally to have a little musical outing." Up to last week, they had had only three such outings in 25 years: in Stuttgart, Berlin and Kansas City, Mo. Houston, where Efrem has led the symphony since 1948, was treated to the fourth.
Midway through the zipping Khachaturian Cello Concerto, which Edmund Kurtz...