I had a couple thoughts, for which I apologize if they were already addressed here and I missed it.
I agree with Mr. Chamkis on using rotary switches for stepped gain. To me the coarse gain steps are not a big deal versus the better tracking and reliability over pots. I'm comfortable with post processing, so with a reasonably quiet recording signal chain, normalizing to make up for 4 or 5 dB of "wasted" headroom is no biggie.
I also like the "stereo gain + balance" configuration, since a portable, two channel mic pre is usually going to be about stereo. Dialing in an offset during recording could be handy for several reasons, as discussed earlier in this thread. But it seems, for the same reasons that separate gain switches are not so useful, that the offset is not normally going to be huge. And a solid
0 position is very important.
So how about making the balance stepped as well? It seems you could use the same 6 position rotary switch used for the stepped gain. Using 5 of its positions, you could adjust the left/right difference to two different levels, say 3dB or 6dB, with a nice solid
0 position in the middle.
A 7 position switch would give 3 levels, and if
that same switch were also used for gain could give 0-60dB instead of 0-50 (or whatever).
I wonder how soon Mr. Chamkis will wish we never heard of him? Peace,
Sanaka