Yes I agree with that! Those cans have over-emphasized bass to no end without a doubt, but there are certain areas which are simply reproduced as distortion with my HE-6 but as sound with rumble with the Pro 900.
Examples - thunder, followed by a lightning. the thunder is reproduced as a big scrumbled distorted noise on the HE-6 whereas on the Pro 900 it sounds like thunder.
Other example is a dropped bomb, exploding- on HE-6 the explosion is a messed, distorted "fhskjf" but on the Pro 900 it is reproduced to the latest bit, like that deep explosion should be.
Then again my HE-6 (which might be the only Hifiman with rolled off bass? according to the graphs) is my only HIFIMAN point of reference so I generalized a little bit there.... Sorry if it differs with other models. Sorry again
And I said I likewise do to... just complaining about this one single little tiny wee flaw :)
The bass on the hE6 when properly amped with power and I mean at least 15 watts is explosive.. I used an 80w wat tpower amp and it never distored until I used my Taboo on comples passages the amp simply gave out causing distortion,. I will say this again and IU have purchased the he500 again the he6 when properly amoed and I mean powerful amps is the best headphone I hav eowned or heard. Sadly I sold it off because my SX980 was having some issues or I would still own both. The bass on the HE6 when amped properly is to die for