Ok I couldn't wait. After about an hour and a half of listening, my initial impressions are very positive. The Kann Alpha is perfectly capable of driving these. I switched to high gain and anywhere from 60-80 is comfortably loud depending on the track, with 80-90 standing next to speaker loud if you want to crank things up to 11. These headphones have amazing clarity, even pushed really loud from the Kann Alpha there is zero distortion or loss in quality - should be really fun to experiment with some real head-bangers and get that clarity at high volume.
The only other initial reaction I have is that these are heavy. They're very well built and right from the unboxing everything feels high quality and well put together. They're very comfortable once you get the headband adjusted to the right fit, but you are aware of them.
Anyway, need to get back to work. Will listen more over the weekend and give a more detailed review.