You ask if I know of more recordings, the answer is yes, he played several more when I was friends with him in the late 1960s. I heard Eri Tu from Ballo in Maschera, an excerpt from Aida, Act III and a Toreador Song that I remember.
You are correct in calling me up on being loose about mics. You are correct that as early as the 40s there were floor and area mics but all they did was add a little volume and boost. The singers still had to project to the back of the orchestra and up to the balconies with only minor help.
