Still detecting my 1Plus2.2 pulling away from the original Ref.1 after upgrading the cable. Not much more we can do about this I'm afraid.
I have no Idea how the Ref.1 Too holds up but the outcome is looking grim here.
I would lean more towards slight product variation over burn in differences personally.
Over my time here I have heard a few occasions the same model IEM sounding slightly different.
Even from the well known Westone brand being one of them.