Of course, Balanced Audio Technology (BAT) comes to mind as well as the Aesthetix (sp) Callisto. Also, any of a number of tube pre using transformer-coupled outputs usually also offer balanced outs, such as Audio Note and possibly the soon to be released WAVAC "reference" pre-amp. I'm sure there are others as well.
Tubed pre-amp w/ balanced outputs?
Could anyone suggest one? Do they exist?