You find out, working with analog vs. digital computers that the results are always the same with digital and never with analog. Perhaps it is this lack of precision that they hear.
I'd have to see a lot of double blind studies before I would accept that even a small minority of the people can tell the difference.
I work both Grass Valley and Chico music festivals and frequently see people claiming the superiority of their brand of amp sometimes with tubes. But then they stick a mic in front of it and run it through an all digital system so people can hear it and nobody ever complains or even comments on any difference.
In any event it is clear that "better" is fairly sunjective. If you doubt this listen to a Chinese opera.
Modeling is becoming almost perfect now (I am happy with my stuff and it isn't as flaky as when you have tube bias poop all the time). Most musicians (that fought digital tooth and nail) are using pro-tools now because it's 10% the cost and more exacting to get an album out. And almost no one makes $$$ on albums anyways, so get it out, and start touring.