I hope the new one turns out well - I love the heck out my current one.
The only improvement that I can see really is the potentiometer; low volume channel balance isn't as nice as I would ideally like, but as I don't use that feature anymore it's not an issue for me now. Stepped attenuators are really nice, but those are rather pricey.
Stepped attenuator would be nice.
I want to see easier switching between variable volume pre-amp mode and line-out headphone mode. Since pre-amp mode (very useful) degrades the line out, it should be easy to switch back and forth. (This is the wrong place to use an internal jumper like the old StageDAC in my view.)