It’s very subjective. Some people don't like the hd-650, some do. i don't think you can rely on somebody's else opinion when buy headphones. It’s very sensitive personal area and unless you try them yourself it's absolutely pointless to ask 3d parties opinion. For me the hd-650 are the best for...
And from Rohan some crash course (this one and the above post are to destroy urban myth that the HD-650 are difficult to drive because they are 300 Ohm):
Generally, a properly designed desktop headphone amplifer can drive high and low impedance headphones and can drive headphones of any...
This an opinion of the sound engineer Nuffink.
It beats me why people get so confused about headphone impedence.
The loudness of any transducer (headphone or speaker) for a given input is called it's efficiency. It's measured in Decibels per Watt Meter or dB(W/m). It most definitely isn't...