Any recommendation for a tube amp? Interested to try one.
Budget?
I can vouch for the APOS Gremlin and Xduoo TA-66. Both great budget options, although the TA-66 has the edge as a OTL tube amp.
The one I've not heard is the Bottlehead Crack that for a long time has been the defacto recommended for the 6x0. Although it's more expensive than it once was.
), even then it's always worth keeping the HD6XX as a reference as it's one of the most compared headphones out there.