In the 90s, the late Sir Georg Solti asked American soprano Renée Fleming if she would sing [Isolde] for a production he was planning. Fleming looked at the score, decided that her voice would never be the same, and refused.Renée Fleming? Honestly? A singer with a smallish voice*, no depth in her low register, and not much thrust on the top? Was he planning to do Tristan with an orchestra of 50, or what?
* I heard her live on a gala some years ago, along with a range of other sopranos and mezzos. Bigger than Janet Williams, a very light soprano, but noticeably smaller than Swenson, and nobody's asking her to sing Isolde.