Go to the sound science section and you'd see how many people say the DT880s sound almost exactly alike. Differences are blown out of proportion the same way ss amp differences are.
Depends on the amp and it's ability to push voltage. The same sensitivity but more resistance means it requires more voltage to power properly. Some amps just cannot push out enough voltage to discern the differences between them.Yes, the sound signatures are similar but in quality wise they are not the same SQ wise. I've tried them all on the same amp that can push more than enough voltage (AMB m^3 DIY design amp, one of the best out there). AFAIK, only me and joker have heard a majority of different DT770, DT880, and DT990's on the same setup.
Not to discredit you and Zombie's claims, but people like to turn a 5% difference into a 25% difference, same as they do with amps, which are meant to amp a headphone, not transform their signatures into something else.
In any case, with their setups and amps, they have tested a 32 vs 600 ohm, and a 250 vs 600ohm. The differences to them was so insignificant that they'd say it wasn't a difference. If you have to buy a $1000 amp to discern the differences, well... its just stupid to amp an amped Dolby Headphone signal with something so expensive just to justify getting the 600ohm.
Also for the purpose of gaming, the slight differences wouldn't even be noticeable as you are focusing on the games and not every particular nuance of the sound.
600ohm is overkill for the Mixamp, and can sound worse due to its inability to drive them well. So to drive them well, you'd have to amp the already amped signal which might be worse than just amping the 32 ohm with the Mixamp only.
Like I said, go to the sound science section to the DT880 thread, and you'd see just how many people can't tell the difference between the 250 and 600ohm. Its a huge debate, that will never end, but if the sound is so close to be debated, I'd rather get one more versatile and able to be properly driven by more source and amps than just shine with a ridiculously overpriced amp that not many can afford, and even then that's debateable.
If its one thing I learned on Head-Fi, its that people love to make something miniscule into something grand.