SH, I agree with you regarding the balanced I/O. (my amp has balanced and unbalanced inputs. As long as it's close to the preamp, I go unbalanced) But, why would the extra step cancel out even-order distortion? Why would it cancel out anything? I would think it should *add* if anything.

The way I understand it, there are a couple of ways to design a balanced output. Either with a transformer or a differential driver circuit. Is one of those implementations prone to cancelling even harmonics (of distortion).

Cary