(forgive me for adding more to the suggestion pile)

I was recently comparing my SHP9500’s, HD600’s, and Sundara’s, and discovered something. (this isn’t meant to be a review of those, but those are just the examples I used)

Even though I EQ’d all of them to be nearly perfectly flat in frequency response, they still sounded significantly different in a way I couldn’t quite put my finger on. I spent some time trying to suss it out and came to the conclusion that the SHP9500’s severely compress the dynamic range of the audio.

So while, yes, the response is flat on the SHP9500’s, the amplitude of the music is also pretty flat, with quiet sounds being nearly as loud as loud sounds, whereas on the Sundara’s the quiet sounds are truly quiet.

This could just be confirmation bias or some other nonsense on my part, but I felt like that difference in dynamics had a huge impact on my perception of soundstage, instrument separation especially, and the general feeling of clarity.

On the SHP9500’s, all of the voices and instruments felt muddled together and difficult to discern one from another, but on the Sundara’s it was incredibly easy to discern the individual instruments and voices. On the SHP9500’s, the sound stage was decently wide, but everything felt like it was a speaker playing a recording of the sound instead of the sound actually being there, whereas on the Sundara’s, even with a soundstage of approximately the same width, it sounded like the source of the sound was actually there with me, instead of being played through a speaker.

So I sincerely believe that a Dynamic Range Compression/Linearity test of some kind would be hugely beneficial in determining the quality of a headphone, perhaps moreso than any other measurement besides frequency response. (a bold claim, I am aware)

So if only one new measurement type gets added in the future, I would like to be this one. I hope y'all are willing to consider it. I did see that it was on the list of “measurements not included” on the existing spec. So I’m happy you are aware of it at least. :)

As far as the specifics of the test, I’ll leave that up to y'all, but I have a hunch that different frequencies will actually have different levels of compression on different headphones.

Anyway, thanks for reading my ramblings. :P

EDIT: Specifically, I am talking about the displacement of the diaphragm of the driver relative to the power of the input signal. The graph could easily look something like an audio compressor graph.