I think the Mjolnir is my next move, the loss of the plush sound of tubes is what stops me, but I guess I can keep the Lyr around. The only "higher end" SS amp I own is the HA-160 and I feel like it thins out the 650 too much, but I like what you describe here.
Bravo on re-terminating the stock cable, I tried with one my dog(wife's dog) chewed on and it did not go well.
I can't remember--is dog slobber an insulator or a conductor? . The HD650s have a very full controlled sound out of the Mjolnir. The HA-160 may be a bit underpowered to really kick the HD650s. I love the hybrid tube flavor if the Lyr, but the detailed energetic signature of the Mjolnir is addictive with dark headphones like the Senns and the LCD-2/3.