Hahaaa! I thought these cans sounded just... silly, when I heard them. Glad to see this verification of my ears.
As for speed, it seems people confuse lack of bass with speed. Yes, if you take away the bass notes, the sound is flatter and seems to linger less. But that is just a frequency response error, not any kind of speed thing. The base notes all have the same frequency and move very slow anyway. If you sped them up, they would change their sound! Anyway, we digress. Kudos to a few reviewers who noted the errors in mid-range.
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Aahhh, the fast bass question.
People tend to make this way too confusing, understandably. Someone needs to come up with a better term than "fast bass" because, as you pointed out, "speeding up bass notes" would just change their sound. The slower the drivers are moving, the lower the frequency.
What fast bass really refers to is the speed at which a driver resets. A simple example is this: given level matched volume, a little 3" driver will have less space in between consecutive 50Hz beats than a 8" driver, because the 3" is simply working harder. This decay is measurable and can partially be the culprit of muddy-sounding bass. The faster the BPM of the beats, the more noticeable this lack of space is in the 3".
Servo subwoofers address this problem by actually having sensors that analyze this "decay" live, and then feed that data to servos which try to compensate (definitely using less technical jargon than I should).
Nonetheless, most people don't even understand what they're saying when they say headphones/speakers have fast bass, let alone exaggerations. They do indeed somehow not understand that vibration speed decreases in tandem with frequency. Reset speed is separate from this, but most who applaud something for its swift bass never mention it.
So, I guess a better term would be "reset speed", but it's just a weird phrase to use in discussing bass, I suppose.