"You have to compare the same high quality headphones, the amp with the same DAC, with the same recording, being played through a high quality filter bringing everything down to 44.1kHz/16bit."

I agree. If there is a methodologically sound study showing that people can actually distinguish (>50%) between 44.1kHz/16bit and 192kHz/24bit on the same hardware [at exactly the same dB SPL], then I will be really surprised. It's not physically possible to hear those differences, as far as I understand it.