Hi Justin, since I am a member of Graham's forum and like his amps I once asked him and he stated no just the way Sennheiser UK chose to show their cans.
Fireball, we all hear differently and your best bet would be to listen to some of the amps you are interested using your HD650. I have owned the X-Can (original), X-Can V2, and X-Can V3 all stock and modified by Mike (Pinkfloyd) of Rock Grotto. My favorite was the X-Can V2, it is not the most accurate amp but it gets my foot tapping to the music. Good luck on your search, it is a big part of the fun.