Varnay sang all three principal roles in Verdi's Aida: the title role, Amneris, and the high priestess (according to her autobiography sometimes in the same performance in which she sang Aida!). That she is terrific in her Italian roles shouldn't come as a surprise, but it often is so associated is she with the German repertoire. She is on top of the role from the first moment, reacting to her colleagues with spontaneity. She easily passes the high C test in "O patria mia" and all of Verdi's other challenges: a unique artist heard here in her prime.Heidt was a good singer, but Verdi was not for her - at least by the evidence of this recording and the Trovatore she sang that same summer. Perhaps she was indisposed or affected by the high altitude. She doesn't seem to comfortable on any note above an A-flat, a real problem for a would-be Verdi mezzo. Dramatically she knows exactly what to do and when her voice isn't under stress she's quite convincing. The copy of this performance that Opera Depot has is missing the entire Act 4, s.1, Amneris' big scene. There was another version on YouTube that was posted for about two days that had the entire performance (it has been taken down). Heidt does her best, but she simply cannot meet Verdi's vocal demands.Baum drives some people nuts with his bellowing and yet his high notes are impressive. He gets off a ringing top B-flat at the end of "Celeste Aida" and joins Varnay on the top C in the Act 2 ensemble. Valdengo is a fine Amonasro and the two bases are excellent. Picco sounds more organized here than he would be with the young Callas a few seasons in the future.The sound is uneven (volume levels go suddenly up and down), but this transfer is right on pitch (kudos to Andy!).Varnay fans must have this!