Truely Balanced Pre Amps


I was wondering if anyone could give me a list of truely balanced pre amps. Not just ones with a xlr inputs and outputs.
koiman
For a True Balanced Tube Preamp look at Space Tech. Labs.

http://www.space-tech-lab.com/
A 'fully balanced' preamp will not have the signal appear anywhere in the circuit in single-ended mode, except at an input. So all the switching, the volume control, EQ is all in the balanced domain.

So how many drop out when this rule is applied?