The HE6 is beginning to settle in after a couple nights worth of continuous burn in. I forgot how new this pair was, and the aggregate total of hours is even now less than 20 hours. I also let my Odyssey energize for 24 hours and certainly there is something positive happening. In some ways I feel this headphone is a yang to the ying of the HE60. Where the Sennheiser grabs you with smooth clarity, allowing the music to come to it (the HD800 is cut from that similar Sennheiser cloth), the HE6 is hyperfocused, and attacks the music, like a runaway train. The details are not there to be found and picked out, but they bring the listener/observer to the details. It makes for a very exciting sound and there is something sensational and particular to the upper mids that spotlight female vocals. I also find myself increasing the volume, whereas my natural inclination is to lower it. They don't yet grab me like the Sennheisers and the Stax, which adorns the sound with a 'prettiness' not easily described (I think this is tied up with the smooth presentation), but we're definitely moving in the right direction from a few days ago.
Great description. Hopefully you will be able to nail them down soon enough. Female vocals are just so beautiful and delicate on the HE-6, love it!