Mine were silver drivers and they most certainly were a little restrained in the treble energy. Eventually I had to move them and kept the DT 880 as I needed just that touch of missing treble. For the record my hearing is quite good, I had a great solid state amplifier (SPL Auditor) and an Audiolab 8200CD player as my DAC with bit perfect output of lossless files through JRiver Media Center. Other than that the 650 is a fantastic sounding headphone, and frankly for those who like a touch of warmth, the 650 is going to do so much right, and not much wrong.
Afaik SPL Auditor doesn't pair well with HD650.