I agree with you 100% Zapp Fan. Manufacturing tolerances are rarely published, but they often make a big difference, especially in high end headphones. I had a chance to correspond with the fella who designed my headphones and he said that they were aiming for a +/- 1dB sample variation. He told me that most really good headphones have +/- 3dB. I'm sure less expensive headphones have even broader tolerances. The sample variation can end up more important than the target curve if it gets to be too wide.