I am a fan of the Solti cycle on London/Decca. For my tastes, it continues to rise above others for both performance and recording quality. Of the various pressings I have, I find the late English London pressings to be very good. The Dutch pressings have greater clarity, the English a bit more body and bass impact. I vacilate in my preference between them. I don't care for the early pressings, and the two Deccas I have don't sound better that the Londons.
And keep in mind, as much as I like these recordings and performances, they have a place in recording history that makes them more important than their inherent sonic qualities would otherwise merit on their own. Don't chase a sound quality chimera here in an exhaustive pressing-by-pressing search. For superb sonics in an opera, Britten's "Billy Budd" or "Death in Venice" (Decca/London) or R.Strauss "Die Agyptische Helena" (Decca/London) are sonically far superior. So, enjoy the Solti/Wagner for a great performance of incredible music, good (but not superb) sonics, and great historical significance.
Hope this is of some help.
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And keep in mind, as much as I like these recordings and performances, they have a place in recording history that makes them more important than their inherent sonic qualities would otherwise merit on their own. Don't chase a sound quality chimera here in an exhaustive pressing-by-pressing search. For superb sonics in an opera, Britten's "Billy Budd" or "Death in Venice" (Decca/London) or R.Strauss "Die Agyptische Helena" (Decca/London) are sonically far superior. So, enjoy the Solti/Wagner for a great performance of incredible music, good (but not superb) sonics, and great historical significance.
Hope this is of some help.
.