lol not to correct you but dark and warm arent synonyms in this situation
dark=treble roll off
warm=low end strength.
I am sure you find the k712 wayy brighter than the hd650. imo its treble is NOT neutral.
For the hd650 its midbass coupled with lower mids sometimes makes for a thick sound thats not good for a lot of acoustic. So to rephrase the above a lot of people find headphones without treble and sub bass boring. Also it is slow when not amped right and the decay is somewhat smooth but slow making it more romantic and smokey than spritely and live.
The energy of the transient response is why it excels with hip hop and rock etc. Again it is the impact it has that gives it what I would perceive as more bass . Also because the business of those genres they dont sound too splashy with bright highs and no wieght. If I were a JAZZ head and classical head these would be keepers!
But for acoustic and female singers or classical etc they may be a bit thick and loose the sheen of instruments compared to a k712.
Edited by grizzlybeast - 1/21/14 at 7:17pm