The 1906 recording of 'M'apparì' from Martha comes first, and it introduces an aspect of Caruso's singing that rarely finds a place in the critical commentaries: his subtlety. Partly, it's rhythmic.
The move–on and pull–back seems such an instinctive process that we hardly notice it (though no doubt a modern conductor would – and check it immediately). It makes all the difference to the emotional life of the piece, the feeling of involvement and spontaneous development.
Then there's the phrasing, marvellously achieved at the melody's reprise. The play of louder and softer tones, too, has every delicacy of fine graduation; and just as masterly is the more technical covering and (rare) opening of notes at the passaggio.
An edition of the score which brought out all these features of Caruso's singing would be a densely annotated document. It would, even so, be a simplification, for accompanying all this is the dramatic and musical feeling, which defies analysis – and, of course, the voice.
That voice! You may feel you know all these records and hardly need to play them, yet there's scarcely an occasion when the beauty of it doesn't thrill with a sensation both old and new (the first 'Ah!' is one of recognition, the second of fresh wonder). So it is with the items here: excepting the Eugene Onegin aria, which remains external, and the late L'Africaine recording, with its saddening evidence of deterioration. The transfers are excellent.