You're welcome. It's unfortunate that DG had many of the greatest talent and performances and were unable to achieve the SQ of Decca, Philips, etc.
Regarding Levine, I consider him an excellent Mahlerian, I don't think I have any of his DG but have many of his RCA CDs (very good quality). But there it is, DG engineers managed to make the VPO sound bad, as they did too often. Abbado's Mahler with the VPO sounds wonderful, as does his early BPO. I believe some of the recordings are from the 70's and would have been recorded analogue. His BPO circa 2000 was DG digital and is quite listenable with very good performances, although the over-micd orchestra is rather 2-dimensional.
I feel the same way as you, there are some recordings that I don't listen to, even with my well set up digital playback. With streaming it's easy to find other performances with good SQ.