If you want to be able to describe the differences you hear, you can train yourself. I offer a few humble suggestions.
Line up an audio buddy if you can. Conversation about what you hear helps.
Take notes during the session.
Pay attention to the music, not to the sound. Forget liquid midrange, airy highs, tight bass. Instead listen for how the music moves you, what instruments you appreciate, the virtuosity of the players. The best listening sessions touch you emotionally.
In a session listen to the same three to five tracks, twice through. First listen on your regular system. Then swap in the new piece of gear. Then listen to the tracks again. Choose the musical pieces for variety. The second time through, talk about what you hear after each track. Not to repeat myself or anything, but pay attention to music, not sound.
Enjoy!