I do a significant amount of my listening at lower sound levels and have built my last two systems around that goal.
If you want to listen to music at low sound levels, you need to start with the speakers. High efficiency speakers are a must, add quality amplification/ sources and add a little work on the room and you're pretty much there
Adding bass / mid boost may sound satisfying but you end up obscuring detail and micro-dynamics. You're not getting the whole enchilada.