Thank you both for your contributions to sopranos singing "Chi Il bel songo di Doretta" from Puccini's La Rondine. If anybody else wants to contribute, that's how you should look up your favorite soprano.
You're right @frogman about there being a more natural flow from a native Italian speaker. I liked Freni and Scotto's versions very much. Caballe's voice was a bit darker and deeper than I expect, probably from favoring Ta Kanawa all these years. What I love about her rendition is the lightness of her voice reminding me of Art Deco Tiffany lamps.
But here's a treat. A video of Callas singing "Chi Il bel songo di Doretta." with subtitles. You can close your eyes if you listen @mahgister, but I think in this case the lyrics are important. These are upper class people singing about the ecstasy of love and art. Probably couldn't get away with writing those lyrics today. In this video we also get to see the magical Callas: