The skeptics will say that you ruined the sound of R2R by recording them with a normal ADC. And then playing them with ordinary DACs. So who are we trying to convince with such a test?
I don't think anyone who has a strong opinion will change its mind, true. As far as I know, R2R ADCs aren't widely used in the production of music anyway and that doesn't prevent skeptics from holding their beliefs.
The interest/fun would be, as it was in archimago's test 1) is the difference audible 2) which one is preferred.
That test was really eye-opening: while I apparently could identify the best measuring device by ear, I still think I could have been just lucky at my n=1 personal level, since the differences were so small. In casual or standard listening scenarios, I am 99% sure I wouldn't have noticed a silent switch from the cheap motherboard to the reference device.
On point 1, so far, the common wisdom here has been "likely not audible anyway" for most DAC differences (that's also my opinion), but that hasn't been established (except maybe by the archimago test).
On point 2, a consistent strong preference for one type of device or the other could illuminate an eventual psycho-acoustic effect. The "gold standard"
blind speaker listening test does precisely that btw, it provides evidence that certain design parameters/sound characteristics correlate well with user preferences.
It could happen (I hope not but I don't know) that most people prefer a distorted/low SNR signal, yes.
primary outcome: ability to discriminate
secondary outcome if primary outcome result positive: preference.
Now, taking the "nightmare" scenario for some here which would be like 80% of the users can tell there is a difference and out of those 75% prefer the "poor" boutique device, such a result might be poorly received, but science should accept annoying results. Those unpleasing results to happen: in other fields, people have strong preferences for foods rich in highly refined short carbohydrates (aka junk food)