Plot: The stage concert starring Victoria De Los Angeles, Barry Morrell, Elizabeth Doubleday, Virginio Assandri, Arthur Newman (in opening scene of Verdi's ""La Traviata""), Marian Anderson (""Heav'n, Heav'n,"" ""My Lord, What a Mornin',"" ""Roll, Jord'n Roll""), pianist Artur Rubenstein (Rachmaninoff's ""Rhapsodie on a Theme by Paganini,"") Alfred Wallenstein conducting the Symphony of the Air Orchestra, guitarist Andres Segovia (Gavotte by J. S