You and some others here who have bought HM1 blind does it based on reviews or friends who heard it. I have no real problem with that. My issue is that it's not enough for me to even consider ordering the HM1, let alone buy it. When I read about the HM1, I am struck by the fact that it is quite small and light, and if it is something really good class A amplifiers, which can drive hard drive headphones like HE6, usually are, it's quite large and heavy. In addition, a good amplifier can usually double the output power from 30Ω to 15Ω. Something that HM1 does't do according to Zähl's own data. Does it matter? My experience says that it does for TOTL class A amplifiers. That it weighs lightly indicates that they probably do not have a particularly large linear PSU, IMO.
I'm glad you write that you don't fault my skepticism in the least. Because what bothered me, in some previous posts, is not that people buy what they want or what they base their purchase on. My problem is the fact that we should be able to demand that the company show pictures of how their amplifier is built inside without be called names for doing it. This is especially important if the amp is difficult to open up.
My two cents