I wish I could say it’s because the volume knob is all the way down.
Did it pass all of the resistance and voltage checks? If so, do you have another dac to test it with, or a different amp to test the pass through function? That would help narrow down if you’re looking at a pass through issue or an issue with the crack. Pass through shouldn’t be a problem. Once you have the check numbers, post them with the issue on the bottlehead forums and doc and Paul will help you as well.
Thats a nice looking amp!