Sennheiser Orpheus. A mere $12,000. IMO an inexpensive but VERY VERY neutral headphone is the Etymotic ER-4S. You need custom earmolds to get the most out of it but if you want something with zero coloration and utter neutrality, they're the ones to get.

A side benefit of Etymotics is that they naturally block out noise and seal to the ear canal so ALL you hear are the 'phones. Also, with custom earmolds they fit very comfortably and are not irritating which makes them particularly suitable for hour-on-hour listening. The best place to get earmolds made is anyplace hearing aids are fitted. They'll take a mold of your ear, get the earmolds made, test them on you, then trim them to fit perfectly. Thus, they'll end up being perfect for travel too and block noise more effectively than any active noise cancelling 'phone I've ever seen.

[This message has been edited by kanebear (edited Nov 20, 2003).]