" Hmmm....guess with a different DAC .... "
IMHO that hits the nail accurately on the head. In all the decades of messing around with digital (I'm 82YO now so have been at it awhile) the no.1 lesson I've learned is that the weakest link in the chain is the DAC. Those "subtle" variations audiophiles detect are more due to the DAC than any other one single component. My thinking FWIW, is that changing headphones or amplifiers is a waste of time, money and effort if the DAC is not up to scratch.
I am now listening to sublime classical music reproduction from FLAC files handled by Roon on this powerful W7 64 bit PC -> Auralic Aries bridge -> balanced digital out via Canare D206 cabling (and the quality of that cable IS important as it is an 8M long run) -> YGGDRASIL DAC -> Auralic Tauris MkII -> Sennheiser HD800S headphones.
And I have a pair of Focal Utopias but a visitor kindly damaged them by overloading them (he is a bit deaf and will not admit it) so they are currently back in France being repaired for God knows what cost. The Focals did sound a bit different but I would not swear they were "better" so will wait until they return to comment decisely on that. In the meantime I'm more than happy with the 800S as they are lighter and more comfortable anyway.
Bottom line from me is guys, stop wasting your money on lusting after other amps and headphones - fix the DAC first.