Howdy Amir & other ASR members,
I am an ASR newbie. But just wanted to say that I'm glad you've decided to start doing some headphone measurements, in addition to the other audio gear you've been doing. I wish they could've been done with the new HBK 5128 system. But I understand that was probably too big a lift to start with.
With a little help from Pierre Aubert's database, I've found both your reviews and spinorama plots of loudspeakers very helpful indeed! So thank you sincerely for all the work that you and your members have put into those!
I have one small request. And that is to include diffuse field measurements with your headphone reviews and measurements, in addition to the raw and Harman compensated plots.
Diffuse field graphs would have a couple of advantages. They'd remove the dominant ear resonances making it easier to assess a headphone's linearity and tonal balance (see my comments below re sound power). They would also allow your measurements to be more easily compared to the DF compensated measurements of some other sites. Including those which use a different measurement apparatus than the GRAS system you're currently using. And they would make it easier to compare your headphone measurements to the frequency response of loudspeakers, using the diffuse field equivalent in that domain, otherwise known as sound power.
If you ever decide to invest in a full head and torso rig, such as the HBK 5128-C or D. Then it would also be interesting to see some raw in-ear frequency response measurements of loudspeakers in a typical home listening space, made on the same rig that you use for headphone measurements. For comparison to your raw headphone plots. Maybe there is also a similar dummy head and torso that could be used with your current GRAS ear simulator for something like this as well.
In the meantime though, I think comparing the diffuse field headphone measurements to sound power is probably the next best way to accomplish this, rather than using the Harman curve. Others may disagree though.
Thank you again sincerely, for all your time and efforts. And the amazing resources you provide here at ASR.