consider yourself lucky, I was getting a headache after 20-30 minutes
The clamping pressure wouldn't be so bad if they chose a different material for the pads - but the hard memory foam is constantly pushing against your head which makes the pressure difficult to deal with for extended periods of time. The softer velour of the HD700/800 is much softer but would put your ear too close to the driver of the 650s thus changing the sound. It's pretty crazy how tightly a headphones sound is coupled to its pads, shape, size, and material choice.