There is, but getting good microphone placement for headphones is difficult. http://www.roomeqwizard.com is the standard for this with home enthusiasts, and many affordable measuring mics have calibration files (typically provided by the mfg), but the frequency response of a headphone on YOUR head will be much different than having them free-air with a mic between the sides. They have model heads made from various materials to help with this, and measuring rigs of varying effectiveness have been used for a while. IEMS are even harder to measure, and here as well we see a market from the free earbuds you get at promos to $3k JH Laylas. The accuracy doesn't go up that much above a few hundred dollars, but they do sound different, and some people like + are willing to pay for it.
Ah, and here I was picturing something that combined vacuum bottles, sound baffling, and battery-powered DACs and ADCs so that no wires would have to cross the vacuum barrier. And also, de-wiring the cans of a headset from the headband so you could test each can individually.
Is there no generic feedback-loop-based calibration tool for audio EQ, equivalent to "monitor calibrators" for display gamma ramps?