The most amazing thing about this popular and successful tenor is that he sings an extraordinarily wide repertoire, from Mozart to Wagner, and all the bread and butter spinto roles in between! This is most unusual, and made possible to a large extent by his vocal technique, which is essentially Italian. In the past, German trained tenors were often accused of throaty and muscular singing, a phenomenon almost certainly related to the German language. Most operas performed in Germany are performed in German, and that has implications for vocal production. Kaufmann, on the other hand, sings in a dark and covered way reminiscent of Domingo, and—even more—Giuseppe Giacomini. Kaufmann is basically a spinto tenor, and this has opened the whole range of popular Italian operas to him. Other German singers have managed the Mozart/Wagner leap, but fewer have, in the process, shone in the Verdi/Puccini middle. Here is an example of Kaufmann in a very light and lyrical piece from Così Fan Tutte, a repertoire more characteristically inhabited by lyric and leggiero tenors:
http://www.youtube.com/watch?v=QXEjZqYhgQQ
This is absolutely impeccable singing! It is beautiful, the line is there, the Italian is perfect, and the performance, as I see and hear it, is flawless. Yes, the voice is darker than one usually expects in this aria, but so what? I have always contended that sub-categories of voice genres are ultimately a bit silly. How about "tenor." It works for me!
As I say, the Mozart singer who can also sing Wagner is a known phenomenon in Germany, but here is what is much more unusual, and the main thing that marks Kaufmann as almost unique; his ability to sing the Verdi repertoire in Italian. This video, of "La donna è mobile," is unfortunately somewhat out of synch, vocally, so bear with it please. It is worth it to hear the singing:
http://www.youtube.com/watch?v=5mjgo7c3IW4
I honestly think that is nothing short of spectacular. To me it sounds essentially like Domingo, Corelli, or Carreras in his youth. It is a quintessential Italian spinto sound, and a remarkably good one at that. It is solid, it is convincing, and it is consistent all the way up to the B natural. The best and simplest way I can describe the Kaufmann phenomenon is that he is a great German tenor who sings like an Italian! And boy, does that ever cover a mile of territory in terms of repertoire!
Finally, Wagner. Here is a sample of his Sigmund, against the mighty voice of Deborah Voight:
http://www.youtube.com/watch?v=jUI-3hAVYSU&feature=related
I feel Wagner would have been pleased to have tenors who could sing like this. He is known to have wanted his tenors trained in Italy when possible, and this is why. Domingo has successfully sung Sigmund, at the Met, not all that long ago, to great acclaim. This is first rate singing, and I do not believe it can be faulted.
Finally, I think a word needs to be said about all the silly criticism that seems to abound on Youtube about this great German tenor. Most of it has no meaning. There is one thing that I very much like about opera, and that is that it is a "bottom-line" art form. Opera audiences are not stupid or undiscriminating. Any person (who is not a millionaire) who lays down the money required to see a performance at the Met, La Scala, or Covent Garden, is in love with opera, and expects to see the best. If they don't, they will get very vocal about it, very quickly. A singer who can appear week after week on the stages of great houses, in different countries, and find acceptance, even acclaim, is—in this day and age—a great singer by definition. There is simply no way to survive otherwise. Kaufmann has done this. He sings all over the world, in the world's great houses, in the wide repertoire we have spoken about, and almost always to acclaim. For me, that says it all.