Strange, the HD-650 sounds more balanced to me. I think there's only one other person here who thinks this though!
I don't know if I could stand the HD-650 with a very warm amp. I even get annoyed when I use it with my Clip+ (which is warm) and amp.
I haven't tried the Lyr or any tube amps, but i have a good feeling i'd prefer the HD-650 on very transparent/neutral sounding equipment.