I would never buy something off Amazon with the intention of just returning it after trying it. However IF for whatever reason I am really disapointed in a headphone I would return them. This hasn’t happened yet but it’s nice that I can if I wanted to.

I swapped out the eartips to foams and they feel better. I was experiencing some pain from their large nozzles because my ear canals are too small. Using Sonicfoam SF1 Black 5.8-6.5mm (Snall)

Once you know what the difference is it’s hard not to tell the difference. For me its the dynamic range, the contrast between the soft or loudest sounds. Something like Pink Floyd Dark Side of the Moon is a good album to use to test dynamic range. The more compressed a track is the closer all the different sounds are in volume.