Agreed. This was my impression also. It would have appeared by many accounts that the 6khz peak issue had been solved. I had even requested a late serial number with this in mind.
Although the tolerances are still very tight across the frequency spectrum, perhaps even more so in the case of the HD-800, the issue could not be missed.
Perhaps in my case not only was the 6khz spike the issue but across the board the freq variations could have produced an almost "perfect storm" scenario.