The link to the
K 1000 Manual in the
AKG K 1000 product page is dead.
Some headphones measurements in the
Build A Graph page give the following image:

These are:
AKG K 601 Harmonic Distortion Products & Impedance
AKG K 701 Harmonic Distortion Products & Impedance
Sennheiser Oprheus Impedance
Stax Omega and SRM-007t Driver Impedance
Also, while the graph of the
Bose Quiet Comfort 2 Impedance does not gives an error, it's totally empty.
Also, as it has been already pointed out,
beyerdynamic DT660 and
beyerdynamic DT880 appear two times each.
DT660 even builds different graphs for each of them.
And
Sennheiser Oprheus is misspelled, it should be
Orpheus.
Hope that helps a little
