Well, I'm impressed. I had zero soldering experience before getting my Crack kit. Thanks to the fantastic directions, I completed a successful build in about 8 hours (seriously, I write instructional documents for a living, and the Bottlehead team definitely nailed it with these). Extra thanks to Doc B for the helpful video on how to solder. I only needed to correct one mistake (scorched the insulation on a jumper wire and had to put a new one in).
I was honestly shocked that I got my amp working on first listen since I was expecting troubleshooting headaches what with my lack of experience with anything electrical.
As for sound, the base Crack is very quiet on my ZMFs with no noticeable channel imbalance. Can't comment on musicality yet since I'm still burning in my tubes.
Question for you all though: Is it best to keep my headphones unplugged when I'm turning on the amp, or can I leave them connected? I get a loud pop when I first plug them into the jack if the kit is on, but that happens with a lot of audio gear.