I spent several decades in international travel with portable high end solutions… well before it was a thing. Go Delta Diamonds.
I guess if I was still trying to take real high end audio on travel I would take my A&K SP2000, with the extra integrated battery pack. Small, heavier than a brick. Sounds great.
But over the last ten years what I concluded was that high end sound and travel do not go together for me. Almost all if the time the ambient noise destroys the high end part of the sound and you are left with the attenuated midrange and bass. The only time this isn’t true is in the hotel. But I find I actually seldom listen… so 95% of the time I’m in high noise situations.
When I bought a set of Bose Quiet Comfort on a whim while in an electrons store in Tokyo… not sure why… I was blown away. It is not that they are high end audio… they are not. But the sound is pleasing and comfy and does not get differentially attenuated in noisy environments… and the noise cancelling is incredibly effective against the roar of the airplane. The sound is carefully crafted to be pleasing in noisy environments.
After that trip, I would put them on the moment I entered the airport (no music, just noise cancelling), listen off and on, and take them off upon arrival at my destination. Completely changed my life… for the better. No more bag full of DACs, amps, headphones, simplicity. I can’t tell you how incredible the reduction of stress that occurred in my trips.
I highly recommend trying it. Your iPhone provides all the music,,, and all you have is the headphone case to bring along. Then when I get home I enjoy my high end headphone system (see my systems) or main system.