That's been my big issue with the DT 770 too, there's really nowhere to go~You start getting into some real meme level headphones in their upgrade path as their tuning is peculiar in the closed back world and nothing unmodded or without EQ really sounds like a more Resolving DT 770.

To that end nothing is really exactly LIKE the DT 770 but better, there's always a compromise so instead of looking to "Replace" them, I've just gone for entirely different tuning profiles as supplementation~ I imagine I'll keep these until they're gone then promptly replace them!