I also think my WA2 trumps my other amps by quite a bit. The Crack is a fantastic amp for the price but it doesn't have near the layers of the WA2, especially with the T1's. In my experience however I do find that my HD650's sound much better with the Crack then my T1's but my T1's trump the HD650's with the WA2, but either way they BOTH sound better on the WA2 then they do on the Crack.
I also have a Schiit A2 and an older LDII++ and I can state that without a doubt both the Crack and the WA2 are leaps over either of these amps with the A2 being my least favorite.
BUT, here's the catch, the WA2 is also far more expensive then any of the other amps and when buying one needs to consider this as well. For me the WA2 is well worth the extra coin but if my budget was tight then the Crack would have kept me satisfied for a long time and if my budget was REAL tight then the LDII++ with the right tubes would have done the same. The A2 however, nope.
So my .02 is easy, if you have the money and want a top notch contender then the WA2 is one to look into. But if you are on a budget and don't mind the build (which is really easy and quite fun) then go for the Crack. You won't be disappointed either way!
Just an FYI, I had already owned the WA2 before I bought the Crack. The Crack was purchased pretty much just to see what all the fuss was about. I had planned on selling it after I got to use it for a while and well, I'm not, so that's gotta say something about the quality of the sound it produces. Lol