I understand the whole impedance concept and its effects.
I ask this question because even when I set my soundcard to output 64 ohms max to my 300 ohms HD 650, the volume is still very loud. If I go on max volume at 300 ohms, I swear to god, my headphones become loudspeakers. As loudspeakers @ 300 ohms, it's LOUD.
I mean, are you guys using headphones inside a nuclear power plant, so you need low impedance headphones with high SPL to set the volume so high in order to surpass the power plant's sound pressures? Do you guys actually use the deafening volumes that the near 300 ohm levels provide?
That's what I get when I see people everywhere saying it's "hard to drive" like as if they were complaining about it. Hell, even when I plug my HD 650 on cheap portables, volumes are pretty high. I'm definitely missing something on this whole "hard to drive headphones" thing.
Please, clear my mind.