I really don't know why these aren't getting more attention. They sound fantastic!
I compared the HP100s to my K167s, and the HP100s easily outperform the AKGs to my ears. The HP100s are more refined, the highs are clearer and vocals stand out more. The K167s bothered me with what I can only describe as hollow, recessed vocals/mids. The bass on the HP100s is pretty much perfect IMO. I love feeling the bass more as opposed to hearing it. The sub bass of the HP100s is truly subterranean in it's depth. It's like feeling distant thunder. It digs very deep. Now, the K167's bass goes deep as well, but it is a bit overpowering to my ears and can be a little boomy at times. It's definitely not as tight as the HP100's bass.
Let's put it this way. The HP100s sound so good, that I am using them as a closed alternative to my HD800s! Now, I'm not saying they perform as well as the HD800s but I actually did swap back and forth between the two to compare them. The HD800s are quite a bit more refined, and can keep up with complex songs even when things get busy. The HP100s do a very good job of this as well, they just can't quite match the layering, separation and overall refinement of the HD800s. Of course, this is a $200 vs $1500 battle.
I am going to be comparing them to my A900x's later today... something tells me the HP100s aren't going anywhere.