As mentioned above, Deja Vu Audio makes custom amps. These days, they focus on fairly expensive replica/rebuilds of Western Electric amps. They do get trade-ins of vintage tube amps as well as some of their older, and more affordable, past models. Most of those older amps are pushpull triode amps, though some are tetrode/pentode amps. As a Audio Note dealer, I am sure they can make good recommendations on suitable amps for the AN-K speakers.
There is an interesting builder named Tube Audio Labs that makes some very nice looking amps. I have not heard any of their builds, so I am going on the pictures and the kinds of amps they choose to clone--Korneff, Western Electric, etc. In other words, the builder copies good stuff.