Krutsch
Headphoneus Supremus
Hmm... after a ton of back and forth listening, I tried the Sennheisser HD820 and HD660, MDR-Z1R, MDR-Z7M2, MDR-Z7, Pioneer SE-Master1, Audio-Technica ATH-ADX5000, HiFiman HE6se, and my own MDR-1AM2, I decided to stick with my MDR-1AM2
....
I am just going to throw out an opinion, based on my own listening experience. Be careful judging headphones with a lot of back-and-forth listening. It takes time for your brain to adjust to the new sound. What I have learned at meets is that your brain sort-of has a baseline for judgement that is aligned to the 'phones you listen to the most (and/or most recently) for a period of time. I am intentionally being vague, as the time required for "brain burn-in" varies between people and equipment.
So, it should not surprise you that you ultimately fell back to your existing 'phones of choice: your MDR-1AM2.
IMO, you really need to "live with" a set of cans, acclimating to their sound across a variety of music selections, before deciding what you like. That's why so many head-fi'ers are constantly buying and selling headphones (sometimes selling and re-buying the same brand/model).
Jealous of your shopping experience, nonetheless... last time I was in Tokyo for work, one of our salesmen took me to a store like that, but we didn't spend enough time there to listen to gear.