It will probably be a few years before I upgrade my headphones next, but once I do, I'm considering something along the lines of Sennheiser HD 800, Oppo PM1, Beyerdynamic T1 or Hifiman HE-560.
The final choice will be whichever compliments my HD 650's best and plays nicely with BH Crack (which will most likely be my next head-fi related purchase.)
The final choice will be whichever compliments my HD 650's best and plays nicely with BH Crack (which will most likely be my next head-fi related purchase.)