Suggest a headphone that is a meaningful upgrade from HD650, in around 50-60k

Suggest a headphone that is a meaningful upgrade from HD650, in around 50-60k budget. I have Topping DX3Pro+ DAC/Amp to drive them.

My preferences:
- Open back
- Warm and musical sound
- Good soundstage accuracy, decent size
- Improved sub bass coming from HD650