All measurements are made using an amplifier driving the headphone. But, I suspect you mean that you want to see some measurements that indicate the amp-headphone interaction. There is only one type of measurement, the low frequency responce, which indicates the interaction between amp's output resistance and headphones impedance.
Orthodynamic headphones, like HE-500, excibit purely resistive impedance and so their low frequency responce is not at all effected by amplifier's output resistance.
So, I am not aware of any measurement that will indicate (for orthos) the amp-HP interaction.