yes

ETA O2 has the best bass ive heard from a headphone.

I find the efficiency of the hd600 to be high enough to be powered off a macbook pro or phone, despite the high 300ohm impedance. can’t be said for the hd650, that requires decent amplification for it to wake up.

the audio drivers and background processors affect the sound. something you just gotta try yourself to find out.

changes the sound dramatically.

trust me when I say this. downgrade the operating system to the original iOS 4.3 version and you’ll hear the difference in sound quality. paired with low ohm, high efficiency headphones like koss or grados, It’s unreal how good it sounds.