From a superb 4 CD set on the Preiser Label,  20 famous Wagnerian singers:

Lotte Lehmann, Gertrude Bindernagel, Nanny Larsen-Todsen,
Maria Muller, Maria Reining, Lilly Hafgren, Karin Branzell,
Maria Olszewska,Margarete Arndt-Ober, Hans Hermann Nissen,
Alexander Kipnis, Joel Berglund, Michael Bohnen, Emil Schipper,
Heinrich Schlusnus, Set Savanholm, Gotthelf Pistor, Curt Taucher,
Erik Enderlein, Franz Voelker.

                               (83 minutes)

I think you will enjoy these 17 tenors singing the famous aria
from Gounod's "Faust" and will be able to understand how
various tenors approach the top note, because that alone is quite interesting;of course, you might be hearing some of these artists
for the very first time, and I think you will be pleased.

Richard Tucker, Enrico Caruso, Beniamino Gigli,
Neil Shicoff, Georges Thill,Giuseppe Di Stefano
Rolando Villazon, Nicolai Gedda, Jussi Bjoerling,
David Devries,Miguel Villabella, Lucien Muratore,
Cesar Vezzani, Alfredo Kraus, Gaston Michelettti,
Albert Lance, and Charles Rousseliere

                              (93 minutes)

This podcast features three of the finest mezzos in opera history:

    Kathleen Ferrier       Janet Baker         Stephanie Blythe

                                 (88 minutes)

I had a problem with the narration for this podcast, so you will
have to live without the benefit of my voice for this one. I was
so thrilled at Joyce Di Donatos' fabulous rendition of the final
aria of Cenerentola at her recent recital, that I decided to do
a comparison of several other mezzos in this same scene. They
are as follows in order:

Ceclia Bartoli, Olga Borodina, Ewa Podles, Maria Callas,
Veselina Kasarova, Agnes Baltsa, Marilyn Horne, Conchita
Supervia, and Joyce di Donato. 

     I sincerely hope you enjoy the podcast!

                                   (68 minutes)

Scenes from operas in the "Verismo Style" sung by some of
the great Italian interpreters,including:

Tito Schipa, Aureliano Pertile, Bernardo de Muro,
Beniamino Gigli, Alessandro Valente, Giuseppe Taccani,
Ferrucio Tagliavini, Riccardo Stracciari, Titta Ruffo,
Mafalda Favero, Maria Farneti, Licia Albanese,
Pia Tassinari, Gianna Pederzini, Cloe Elmo

 (73 minutes)