I too bit the TOS bait and bought most of the issues. I only partly regret it because I discovered so many wonderful interpretations. And wherever I can compare with LPs from the 70's, the TOS are sonically way better except for... strident strings. In fact, the thinness of strings seems to permeate TOS LPs. I narrowed it down to 2 potential issues:
1. Jesus-Christus-Kirche Berlin recordings: these recordings in general sound awful; for example, Scrjabin's Poeme de l'Extase is imho unlistenable; in that church, many great interpretations were mauled by DG's sound engineers.
2. TOS deplorable Optima pressing quality which is appalling at such price level; I just finished listening to the astounding acoustics Mahler 6/Karajan/BPO, yet still not dead-quiet pressing which really annoys in ppp passages.
Note: at TOS, buy everything Gilels! Abbado is also outstanding.
I addressed the 1st issue by no longer buying performances recorded in the JCK.
I addressed the 2nd issue by only buying DG White Label (WL) LPs. They are outrageously overpriced and the packaging is rubbish. However, WL pressings avoid to a great extent the shrillness of violins, are much quieter (but not totally so), have slightly better width and depth whilst increasing clarity and "musical flow".
To check my hypothesis, I bought the TOS MTT/ Tchaikovsky Winter Dreams in both regular and WL, as well as the freshly released Yo-Yo Ma/Nelsons/Shostakovich in both regular and WL. The comparison is embarrassing. WL sounds far superior. Why that is, and why DG chargers double the price for WL is a mystery to me (perhaps not so much the latter: people buy at that price, so DG just goes for it).
I have resigned myself to only buy DG vinyl WL editions, also outside the TOS edition. I was richly rewarded with outstanding releases featuring Gilels (TOS), Yuja Wang, Yo-Yo Ma, Duenas, Zimerman and Sokolov.
This brings me to my final conclusion. DG is incapable of properly pressing vinyl. At the price of its WL editions, DG could release 1-step LPs, which imho is the best that has happened to vinyl in all these years. Imho, sonically 1-step easily beats D2D. WL does not come even close to 1-step.
Competitors (within the same group) are smelling their chance. I just ordered 2 Decca releases out of their Pure Analogue series:
https://www.deccaclassics.com/en/ar...unches-a-new-all-analogue-vinyl-series-277409
Reinard Maillard and Sidney Meyer started the TOS adventure but were betrayed by disastrous quality control at DG's Optima pressing plant. If Decca does not disappoint, I ordered my last TOS WL LPs this week.
PS: for those unfamiliar with the 1-step process: the engineer cuts MULTIPLE lacquers. A metal stamper is made directly from each lacquer. Each stamper stamps at most 500-700 records.