I'm not sure if I'm missing what you are saying, but the HE-6's's and T-1's do not sound anything alike. They are like day and night. The T-1's are 600Ω but drive like 300Ω, and are easier to drive than the HE-6 prodos. However, they, in no way sound anything alike. I love the T-1's and sold my HD800's in order to keep them, but comparing them to the 6's is way out there.
I know that we all hear differently, but the 2 headphones are apples and oranges. Please do not take offense to this, but I have own both, have spent quality intimate time with both and don't see this comparison at all.