Tone is in the Ears
This is the right answer. It doesn't matter what DAW they use to listen to them. You can be pretty sure most analog master tapes (2-inch, for example) have been transferred to digital masters by now for "posterity" (and that's a good thing). However, once the original tracks are digitized, it is just a matter of time before more & more people have access to them. You can share them to anyone and there is no degradation. I imagine it won't be long before such masters are available online for a price.They have access to the original tracks through their industry connections. No software can do what they do.