Although I love the looks of the woo, crack with speedball is a more detailed and dynamic otl than woo2, and a much more sophisticated circuit due to loading the tubes with constant current.
Moreover, for the same cost as a woo2 plus tubes, you can build a mainline which competes with the best of the best on purrin's list, assuming you are willing to take on the build. It is marvelous with hd800s and a similar but more sophisticated circuit as compared to the l2, which Tyll and other long standing industry insiders have praised as their favorite hd800 amp. I guess the build is a little daunting in term of the time commitment compared to a Crack, but I'm surprised more folks haven't tried the mainline at this point.
As to questions about Darkstar a few pages back, you can build one yourself for a couple hundred dollars with the clone boards EC sells. If this is really an amp you want, hire a diyer to build it at a fraction of the Darkstar msrp. Can't comment on its sonics, but reviews don't seem to be glowing.