Very informative is your statement!!!
For the load side of the system of change of devices which are the power, interconnections, and cable; the impedance of output must depend on the type of headphone.
The planar type of headphone like He-5les have lower inductance than HD650 which has motor coil in many uni-directional turns.
Therefore the planar type of headphones can be less dependent than dynamic phone in terms of reactance impact on SQ.
Because the capacitance does not impact the filter function on load-side frequency range.
I need to apply the common sense level thinking to this subtlety driven head-fier domain.
In this way I need to sort out the secondary from primary effect of engineering parameters on SQ.
Consequently leading to my money control for SQ pursuance.