I have a pair of K702 and have ordered myself a Schiit Bifrost. In the future I will probably get myself a pair of HD800, which is why they're in the title. Now comes the amp decision. The forerunners are the Burson HA-160 and Schiit Lyr.
Regarding the Lyr: I am apprehensive about tubes in general, as my experience with them is that they overly color the sound and make the sound more sluggish (less attack and transient response) than solid state amps. Also, since this is such a high powered amp, I'm afraid I might end up blowing some expensive headphones because someone accidentally turned the nob too far. However, I can't ignore the amount of praise I'm hearing with the Schiit Lyr with regards to these headphones.
As for the Burson, I like the aesthetics, I like the fact that it runs cool compared to the Lyr, and the stepped attenuator seems to be like a great idea in theory. Now, the stepped attenuator might also be a downside as I might not get the fine control I want over the volume. I'm also not quite sure how it compares with the Lyr with regards to these headphones.