Nice system. I have similar low volume listening habits and I have optimized my system for it. I have been able avoid DSP so far, though I did try some convolution filters that were supplied with my speakers. My advice is going to be vague, but do everything to optimize your digital system possible, this can bring a level of clarity and depth you did not know was possible. Also consider something like Stack Auva footers or Townsend podiums for your speakers, these can wring out another level of improvement. Clean power is important as well, if you don’t have dedicated lines, start there.
Lowering your noise floor will yield significant results for low volume listening.

