An amp is a total package. One can have excellent damping but fall flat elsewhere. The HE-6 is tough to drive because it has an efficiency of only 83.5 dB.
All of this engineering can be tough to swallow for the lay person. Audiophiles are passionate about their gear and the pursuit of best sound and are susceptible to subjective perception and the stories that circulate. Companies like Monster love to take advantage of this.
Subjective perception is all we have my friend.
Anyways, expert engineers might find it hard to swallow that my HD600's sound great out of a NAD integrate that must have 100+ ohm output. Nice full and tight bass, smooth and detailed top end... Tis better than any HP amp I've tried.