Knappertsbusch could be a stodgy, inert conductor but there is nothing of that in his conducting here. The swirling, fluid phrases of the overture announce that this will be a performance of rare energy - he introduces a flavour of Tchaikovsky's "Francesca da Rimini" in his free handling of the obsessive, repetitive figure building to the climax which almost threatens to become derailed but instantly suggests the destructive passions that lead inexorably to disaster. This is not speedy but always nervy, biting and intense, no stately concert performance.
The big, fresh voices of the protagonists have more vigour and youth than the more marmoreal Flagstad or the mighty Melchior; Helena Braun's bold soprano in particular burns with an intense, slender flame contrasting nicely with Klose's big, warm mezzo as Brangäne. Paul Schöffler is very fine and warm as Kurwenal. Günther Treptow's tenor is a little throaty and "Germanic" but this must be one of his finest performances, his sterling work in Moralt's "Ring" from the year before notwithstanding; he is firm and strong, riding the orchestra easily without barking. To cap a very fine cast, we have the great Ferdinand Frantz as a sonorous, desperate, very touching King Mark. The sound is clean mono and one soon forgets its limitations so absorbing are Knappertsbusch's moulding of the orchestral lines and the intensity of his accents.
In short, I agree with late "Gramophone" opera critic Alan Blyth that this is something of a sleeper amongst the extant recordings of "Tristan" and it takes its place amongst my favourites.
Given its place in history (the eve of Pearl Harbor) this is a first rate performance that shows the brilliance of wartime Wagner interpretation. The Met had some exceptional singers during this period and the recording quality is more than sufficient.
This is a fabulous performance and will take an important place in that small collection of great recordings which I will use for my listening enjoyment of this greatest of operas. The Act 1 Prelude is astonishingly slow providing space to hear, experience and feel almost every note played so I have renewed understanding of the sounds the orchestra makes and I appreciate, again, the place these sounds have in the whole. But the pace varies and it is not all taken as slowly. Bernstein certainly provides the right balance of pace and sound to let these great performers establish utterly believable characterisations and narrative drama. I've noticed some inconsistency in dramatic intensity between the different performances that make up this overall recording and Goodall/WNO/Esther Gray remains my definitive go-to recording.