It seems like most HD-650 owners choose amps and dacs that match the sound of the headphones, rather than complement them. That is, they pair the warm headphones with warm amps. This doubles down on the desired sound character, literally amplifying the strengths. Why not feed the HD-650s with something a bit cooler, with the goal of balancing the warm headphone sound out with complementary strength at the other end of the spectrum in the amp (or DAC)? Or would that just cancel out the strengths of each element and dilute the desired sound of the HD-650?
Pretty much, I assume people love the warmness from the Hd-650's, I'm guessing if the majority of the people wanted a more balanced sound they would have gotten the Hd-600.