I got my Bottlehead Crack, as recommended here, on Thursday night. After waiting a month for it to arrive and an unsuccessful 10+-hour struggle to assemble and wire it, I really just want an amp that will definitely work, not constantly make me worry about bad solder joints, and not electrocute me. I've had the HD650s and HRT MusicStreamer II+ I ordered at around the same time for a while. I would like another (prebuilt) amp to put between these that is a good sonic fit. Also, my long-term goal is to upgrade to a pair of HD800s, so an amp that works well with both headphones (as the Crack was supposed to) would be great. I'm told the MusicStreamer II+ is fairly transparent and neutral, like the HD800s, so I'd prefer an amp to match. Price range: preferably <$600, but after I've spent so much already I wouldn't care too much if I had to spend more.
Update: I am leaning towards the Schiit Lyr, and because of Schiit's 15-day return policy I may go ahead and order one soon. If anyone thinks another amp is more deserving of consideration, please feel free to bring it up. Thanks.
Edited by DarthMarth - 10/6/12 at 4:46pm