According to an interview (in Chinese) with Marc Vincent, the President of Greater China of Sennheiser, they are working on an amp specifically designed for the HD800, scheduled to be launched in 2012.
Marc also talks a bit about the future direction of their mid- to hi-end headphones (the last paragraph below).
Google translation of the relevant part:
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[Here Marc says the Lehmann BCL was used as the reference amplifier in the design of the HD800, but he prefers the SPL Phonitor himself etc]
Marc in the process of answering this question, and even revealed an exciting news is that sound of the sea has now embarked on a new expansion of R & D ear, the upcoming next year. Just ask the author to further expand the sound of the sea the details of the new ear, Marc said that this was the first secrecy, let us breathe. However, Marc and I'd have no generous sharing of HD800 headphones relevant information and the future.
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The future sound of the sea will further introduce more new top-level headphones, go with the HD800 sounds like electrostatic headphones to give the feeling of a wide frequency response, while the price of cover between the price to high price, to meet different groups of consumers.
"sound of the sea" = "Sennheiser" in Chinese...
"a new expansion of R & D ear" means "the R & D of a new headphone amplifier"...LOL 
