Jock.......My experience with the Sennheiser HD800 being driven by the Sennheiser HDVA 600 headphone amplifier is quite the opposite of your comment. I have listened to this headphone for as long as 4 hours at a time without a hint of listener fatigue or discomfort. It is a superior sounding headphone on every level over my previous Sennheiser HD600 and HD580 headphones. Not only does it sound spectacular to me, the comfort level is exceptional as well.
I believe there are endless combinations of source components, DAC's, amplifiers, interconnect, power cables, and headphone cables that will produce various levels of satisfaction with any headphone. Just like speakers, a headphone is only a single link in the audio chain that impacts the final sound, not to mention the quality of the recordings played. For me, the Sennheiser HD800, with the Sennheiser CH 800S balanced cable plugged into the Sennheiser HDVA 600 headphone amplifier, delivers an astonishingly rich level of performance that I find completely satisfying for both short term and long term listening sessions. Of course the general subjectivity of sound weighs heavily on personal preference, so opinions will vary.
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