HOWEVER, and please don’t flame me too hard on this -- I’m just trying to help the OP out with some observations that might be helpful -- I do have a thought that might bring some perspective. So, my analogy between delta-sigma and R2R (and especially R2R NOS DACs), strikes some similar chords with me as comparing solid state and tubed electronics.
Distilling down lots of reading both of audio reviews on sound and scientific observations, delta-sigma DACs tend to measure better overall and sound more detailed and maybe sound quicker. R2R/NOS DACs, on the other hand, don’t measure as well overall but tend to sound more "analog" with richer tonal colors and nuance but can sound less detailed or sparkly in the treble region. Sound a little like the tubes vs. solid state debate? Sure does to me. And, just like in that debate, both can be excellent in their own right and there is no right or wrong -- just personal preference.
Anyway, you have an excellent, and interesting, combination of components in your system, and my guess is you have an idea of what you’d like to achieve from a system perspective with a new DAC. Hope this gross generalization helps at least give you some direction in some small way as to which way you might want to look. Best of luck.