jazznut i found a dsd ransfers from a safty copy of the master tapes and is the best digital version i have heard is this one by SS Laboratory Series
https://www.discogs.com/release/14186172-Wagner-Flagstad-Svanholm-Neidlinger-Vienna-Philharmonic-Solti-Das-Rheingold
https://www.discogs.com/release/12850433-Wagner-Windgassen-Nilsson-Hotter-Stolze-Neidlinger-And-Joan-Sutherland-Vienna-Philharmonic-Solti-Sie
https://www.discogs.com/release/12851210-Wagner-Georg-Solti-Wiener-Philharmoniker-G%C3%B6tterd%C3%A4mmerung
"Master tape used for the SACD
The production master used for this SACD is the safety analog master tape that had been kept for the emergency use and unfortunately got forgotten for a long time.
It had been made by the Decca Record Company in the beginning of the 1970s as a safety master tape, copying directly from the 1/4-inch original analog master tape on a one-to-one basis, and been provided to the King Records in Japan which was the importer and distributor of the Decca records at that time. It would have been used only if any flaws in the metal master prepared for the LP recordings had been found.
But, for its limited usage (only used for the emergency) it had not been on a written record, and consequently, its whereabouts had become unknown. However, thanks to persistent searching by the Universal Music Japan, it was finally discovered and we got the privilege to be given a license by Decca to make a fresh transfer from this safety analog master tape.
The master source currently used by Decca for Solti’s Ring transfer is the digital master tape, commonly known as “James Lock Remaster”, which was made by Decca mastering engineer James Lock who had assisted John Culshaw on the original Ring sessions.
Assigned by Decca to de-hiss the Ring for the 1997 edition CD, Lock made new 48/24 transfers (PCM/48kHz/24bit) from the original analog tapes, applying processing treatments such as equalizing and noise reduction.
Since the original analog master tapes were too deteriorated to make a new transfer (that was said by Decca), all digital discs and digital files that have been issued since 1997, without any exception, were made by using this “James Lock Remaster” as a source.
Therefore, our SACD is the first and only transfer in the world, digitized from the precious master source that had been stored before remastering was applied.
■DSD Recording by Flat Transfer
We have done the digital editing for the SACD in NIPPON COLUMBIA’s mastering studio, and made flat transfers from the analog master tapes converting to DSD signal (digital format of SACD) with a sampling rate of 2.8MHz: playback was done on the STUDER A820 Analog Master Recorder, which had been meticulously tuned by the greatest mastering engineer in Japan, Shigeru Buzawa.
With an aim to make a DSD master as close to the analog master tape as possible, the whole system, including cables (digital/analog/AC), was finely tuned, and state-of-the-art equipments were also utilized; Merging Technologies’ Pyramix System for conversion; Esoteric Master Clock Generator G01X to regulate clock timing accuracy."
https://colnect.com/it/music_records/music_record/11030509-Richard_Wagner_-Kirsten_Flagstad%E2%80%A2_Set_Svanholm_%E2%80%A2_Gustav_Neidlinger_%E2%80%A2_Wiener_Philharmoniker_%E2%80%A2_Georg_Solti_Das_Rheingold