I'm not sure. There doesn't seem to be many measurments of it.

Here is HobbyTalk's measurment of it, unfortunately he doesn't have the same Harman target to compare, so this is comparing with the Truthear Zero https://hobbytalk.squig.link/?share=Hobby_Talk_IEM_Preference_2022_Target,JBL_Endurance_Run,Truthear_Zero

Compared to mine with the truthear Zero https://suporsalad.squig.link/?share=Harman_IEM_Target,JBL_Endurance_Run,Truthear_Zero

I wonder if maybe there is a bit of difference with leakage and the coupler. I'm using just the 711 coupler with the metal end for IEMs which is similar to what crinacle uses. I believe Sean olive measured his in a Gras 45CA with the pinna