I’ve owned DACs since 2007, and overall, their sonic quality seems higher now. In other words, a rising tide (technological progress] generally raises all boats.
But I do hear significant differences between delta/sigma designs vs multibit and NOS (all 3 of my current DACs are NOS). As soon as I was exposed to my first non-d/s DAC, I heard these differences quite clearly.
I understand that NOS DACs (by and large) measure poorly compared to d/s. I'm not an audio designer and just don't care about that. Sound is all I care about.
To my ears, d/s designs tend to sound clinical and cold, edgy, while NOS never does. On the other hand, subjectivity being the essence of our hobby, it must be acknowledged that some people love the sound of clinical, cold edgy DACs.
All I can do is figure out what my sonic preferences are (audio experience buttressed by exposure to music IRL), then select component based on that.