how do *you* discover the right resistor load for a headphone

[Spiug31]

Hi,
I would like to know how people have calculated the resistive load sweet spot for their headphones.

eg. KSC-75 is mentioned as being happier when a 75 ohm resistor is added, DT880 I think I read is happier with 120 ohms etc. etc.

and it is mentioned under Impedance Optimisation at http://www.meier-audio.homepage.t-online.de/


What method have you found to give you best results ?

If a specific piece of kit is used (such as a headphone extension cable with an inbuilt variable resistor) please post a diagram or photo.