sorry but the most important text off all is the hearing test, and many audiophiles prefer r2r over sigma. secondly if you red the article you'd sse that the math is there. if you disagree, just disprove it.
I think you are in the wrong forum. This is Audio
Science Review. Yes, the most important test is listening, but you have to make sure the only factor influencing the result is the actual difference, not your preconceived notions, confirmation bias and beliefs. Thus it has to be a controlled, level-matched double-blind test. I did read the article, and nowhere in it is there any math that supports your claims. It does have a bunch of factual errors - let me point out just one:
Ladder (or R-2R) ADCs and DACs originally came out of the NASA and aerospace missile-telemetry world; Thomas Stockham re-purposed a rack-sized converter from Honeywell for the first-generation "SoundStream" 50/16 system in the Seventies.
No, Ladder (or R-2R) ADCs and DACs originally came out of the NASA and aerospace missile-telemetry world. They came out of work done at Bell Labs on telephone systems back in the 1930's. Remember Claude Shannon?
R2R ladder DAC are very simple in design (I designed and built my first one in 1975 or so), but they have been superseded long ago with better designs for a good reason.