The headphone room had a lot of good stuff. I will just say what I like regardless of price point since that is different for all of us.
My headphone highlights were (in no particular order) the Audeze LCD-X and MX4,, Dan Clark Audio Stealth and Noire X , Meze 109, ZMF Atrium Closed and the Fiio FT7, Fosi i5 PLanar Magnetic
Headphone amps that stood out: the Europa from Moon Audio (expensive but mind blowing) also a preamp, Pass HPA-1c, Auris Nirvana (really liked it), and the Prima Luna 100 (integrated), the iFi idsd phantom (amazing for the price), allnic asra. Oh, yeah, Ampansound products were incredible. Competes the the best.
Focal Room was too loud to really get an idea.
I did not go to Axpona but I have heard a lot of the phones that were at the show. The Allnic ASRA headphone amp is amazing and not back breaking in cost. I wish that amp had preamp out (RCA).
The more expensive Allnic HPA 15000 OTL/OCL has preamp out (RCA). I had that in my home for a couple of weeks, and it was excellent with all the phones I tried it with, including natively with the RAAL 1995 Magna. I also used my RAAL SR1a with this amp but had to use Mitch Barnett's convolution filter with the HPA 15000 to mimic the baffle compensation which that phone needs. Again excellent, but costly.
I am also a big fan of the ZMF Caldera Closed phone. I heard that with a great amp at another show. A shame it is so expensive, I ended up buying a used Meze 109 Pro for $500 for my bedroom. It is not too bad with the Schiit AsgardX amp with integrated Mesh DAC.