Omitting the obvious (ie electric impedance), there seems to be no specs for "Acoustic Impedance" for headphones. I have big ears, so it difficult to find in-e

Omitting the obvious (ie electric impedance), there seems to be no specs for "Acoustic Impedance" for headphones. I have big ears, so it difficult to find in-ear headphones that would match voluminous ear canals. They sound better if I press them very deep into the canal, as the volume is more close to "normal human ear" and impedance matching better.