This thread reminds me of something in another industry altogether computer games - specifically first person shooters. There are many that gives me motion sickness and makes me queasy, and a very few that do not. My sister (besides being a musician) is a reviewer for computer games in her "spare" time. When I mentioned this to her, she said that in the game industry, it is the biggest "I know what it is but no one knows how to measure/manage it" factor. The game studios retain people on their staff that get queasy to test this out. She said that if any one figures this out, he/she will make millions selling the technology to the game developers. Why does one "build" of the software make sensitive people queasy, and yet another build does not?
We were discussing "Portal" and the new "Portal 2" - both developed locally in Bellevue. She and her reviewer friends get sick with Portal 2 and none of them has completed a review of it yet.
Why does Pure Music and Amarra sound different? I suspect that it may be the same thing. To be bit transparent, algorithms should NOT make a difference to the bits delivered to the DAC.