No, the central point is that the analog signal handling before AD introduces vastly more "artifacts" than the AD or DA does.
In addition, nobody cares about "measurable" artifacts (or rather, they should not). What matters are "audible" artifacts. We have measuring equipment that is vastly more sensitive than human ears (e.g. your recording equipment that can pick up signals far above 22kHz). What's measurable is not particularly interesting - what's audible is.
Artifacts do not sum linearly, because they do not originate from correlated sources (unless you're doing something rather unusual).
Glad you can hear the difference between two converters, but I trust you've tested it in a double blind setting?
Hm, no. The discussion was never about analog artifacts vs AD conversion artifacts. Both are present. And not sure why you use "artifacts", do you not believe the artifacts are real? How can the lowpass filter not introduce artifacts?
And absolutely - I blind tested coverters extensively. Mbox2, Black Lion Audio upgraded converters, UA, Prism.