Deutsche Oper web site
I will say this for her: she sounds significantly better in person than she did on the opening-night Tristan broadcast, and in fact so did Stephen Gould (the excellent Tristan). This is one of the rare times in my life that I've heard a broadcast and then heard the same production, singers, and house live, and it adds support for my long-time contention that opera house miking for radio almost always makes singers sound worse than they sound in the house.
Still, I find her vocal inconsistency troubling. Sometimes she'll hit the first note of a phrase dead on, and her voice will have presence and spin, and the phrase comes out with a beautiful line. Other times, she misses, and hooks up to the note she is trying to hit. She was best in tonight's Tristan either singing softly, when she was always in tune and had a consistently good attack, or at triple forte (most of the time). She does always land on the right pitch....eventually.
I don't know what causes this particular problem and her general tonal inconsistency: a voice that is naturally difficult to control; age; wear and tear; forcing for volume; singing beyond your means (a lyric voice in dramatic roles); poor technique; other vocal issues. Anja Kampe was originally scheduled to sing Isolde in this production, and she has it all, a beautiful voice and great stage presence. I really wonder what it would have been like with her.