[Can the Dynahi be operated in unity gain, or is 2 the lowest possible?]

Too bad? You shouldn't be using an amp, you should be using a buffer if you don't need gain. The dynahigh specifically has a number of stages to achieve high gain.

[A Question for Kevin. ????]

When you're adding snubbers, I find that if you use a split-bobbin transformer, the interwinding capacitance is so low you can actually leave it out of the calculation (I'm measuring on an LCR meter).

I'm refering to Hagerman's PSU snubber calculations: http://www.hagtech.com/pdf/snubber.pdf

I can see the ringing on a scope even with soft-recovery diodes (rectifiers generate oscillation in the LC circuit of the transformer parasitics at turnoff). Any ringing of course is elminated by the filters after rectification, but since it's high frequency, it's radio and capacitively coupled to the rest of the circuit, and though it's not in the audio band, it's modulated by the mains AC swing.