Also, 20000 pairs of hd800 sounds also on the optimistic side. It is likely in the thousand digits a year, 20k is a lot. Also, it is typically not in a makers interest to reveal exact sales figures so I would be extremely surprised the hd800 serial number isn't altered as production batches and slight design revisions occur. Especially in these days where users have the stupid idea to join forces in online communities and share data such as calibration charts for their HD800s
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