This recording has been around on the bootleg circuit for years. I remember when it was issued on the Hunt label back in the early 90s and not being sure if I wanted to buy it because I wasn't familiar with most of the singers. Fortunately, I did buy it and was amply rewarded by its considerable merits. This was a concert version so the singers and chorus could focus solely on the music.Karajan begins the prelude very slowly and builds the tension from there. He is less mannered here than he could be in later performances of this score. His singers were well-chosen and don't let him down. Martinis had a steady, dramatic soprano that she used with great skill and imagination. She had an easy top too, something that helps her reach the high C in "O patria mia" with assurance. Her Radames, the Austrian tenor Lorenz Fehenberger, was a cultivated, musical singer who was always good in whatever he sang. His top notes are beautiful too though without providing the squillo that a Corelli or Del Monaco would have. Rankin shows again why she was considered such a powerhouse in the 50s and 60s. Decca signed her to an exclusive contract, paired her with Tebaldi for her first Madama Butterfly recording, and then promptly forgot about her. Nobody ever said Life was fair.Malaspina is a terrific Amonasro (what a voice!) and Petri a properly dour Ramfis. One name correction: the Messenger is sung by the excellent Fritz Sperlbauer, not Spenlbauer. The sound is superb throughout and pitched correctly too.All Aida lovers should have this. I'm not saying it will supersede your favorites, but it's an exciting performance of an opera not done all that well today.