Someone gave me a copy of Placido Domingo's recording of Tristan und Isolde. Nina Stemme is Isolde in this recording. She is incredible. One could wish to hear her with a real Heldentenor. Placido Domingo is not one. His voice sounds somewhat fragile, and the technicians seem to have done nothing to make him seem to balance with Stemme.
I'm not a fan of Tristan. In my search for a Tristan I could make it all the way through, I liked only Nilsson and Vickers. I don't hear Wagner in Domingo's voice. People don't always make the best decisions. Am I supposed to carry on about how old he is? Domingo's tone is self-consciously developed to sound like a certain type of tenor, and this isn't a Heldentenor. He does nothing here to sound like a Heldentenor.
I also own the Tristan with Christine Brewer and John Treleaven. Brewer is very bland compared to Stemme, and Treleaven is almost a baritone compared to Domingo. I think I prefer Runnicles conducting with Brewer to Pappano with Domingo. Do I totally love either one of them? Probably not. How about Stemme and Heppner?