A Tale of Four Headphones by J. A.

Yup! First time (I believe, it's possible I forgot) I saw measurements of the AKG K1000 and they showed much better bass extension than I had expected (haven't heard them myself).
One thing that I found interesting:

• Stax Lambda Pro: "Note the waterfall plot's crinkly appearance, something that always seems to be a feature of planar, surface-driven drive-units"

I know that multiple measurements have shown similar behaviour, of course varying by headphone. In this case I think it's also not easy to pin down exactly what it is in the measurements. It's also not easy to visualize such things. I think in particular ARTA with the IR windowing functions and settings it uses has trouble with this.
I would like some more comments on the math and limitations of the visualizations though, like for example how the AKG K1000 CSD ends up looking so weird below 1kHz. Well, this was 25 years ago and even those measurements looked very promising.