MQ transformers? I thought the Crack was an OTL design and didn't use output transformers?
Personally I've never really been a fan of the whole "balanced" craze. I mean, a headphone doesn't know a "balanced" amp from a hole in the ground and behaves no differently. Bridging is nice if you need to get maximum power from a limited supply voltage, say when using batteries, but if you can specify whatever supply voltage you want, it becomes rather pointless. And when you bridge, you pay the price of higher noise, higher distortion and higher output impedance.