probablly placements of gears and main power conditions and source diffrence or all of them make big diffrences.
since i noticed those diffrence makes big diffrences of SQ, so I tend to not trust auditioning gears at shops..
A shop audition is not useless, but has to be interpreted properly. By way of analogy, if you are trying to determine the differences between kale and spinach in a salad (or for the omnivores-chuck vs sirloin in chili) and you do this by eating a kale salad at restaurant A, and a spinach salad at restaurant B, what you have really done is compared two salads, not kale vs. spinach.... Systems produce sound, individual components contribute to that sound, but it is quite difficult to calcuate the specific contribution any specifc piece of gear makes, unless you have heard all the components incvloved, in multiple configurations, and have heard other systems in the same room (to determine the acoustics contribution to the final sound).
If you bring your poratble music player, loaded with your music to a shop and compare iems or headphones, and it's a quiet environment, and both are equallly broken-in, warmed up, that's a valid comparison. Other than that, you have to consider the audition a data point, not a definitive, accurate compariosn.