People said avoid the Schitt Mjolnir since Mjolnir's high power output is overkill for such sensitive headphones and may actually introduce noise or other sonic flaws, not to mention the danger of damaging those expensive cans. Do yourself a favor and look for something else.
However you can add these amps to the list:
Used HeadAmp GS-X
Used Cavalli Liquid Fire
I'm still looking for a good amp to pair the TH-900. I chose the Matrix X-Sabre as my DAC.
My impression after reading about the Bryston BHA-1 is that it has very high gain which seems to be a general problem with it for people listening at moderate levels with for example Sennheiser HD 800. I would assume this problem would be even worse with rather sensitive headphones like Denon AH-D7000.