I don't have an Auteur, so can't comment on amp matching for it. But I do have a blackwood Aeolus & silkwood VO and know how well they work w/pretty much any tube amp.
FYI, the every well respected 2-channel tube amp/preamp designer, Mike Sanders (Quicksilver Audio) now offers a headphone amp, and I've been following it pretty closely. Actual reviews are sparse, but user comments are almost uniform in praising the sound of this transformer-coupled design. I may pick one up in near future...you get a lot of amp for $998. Plus, unlike many other tube amps, this one would actually fit on my crowded desktop.
https://www.head-fi.org/threads/quicksilver-audio-headphone-amplifier-any-opinions.928371/
http://quicksilveraudio.com/products/headphone-amplifier/