I finally, today, figured out what I'm going to do with this project
I'm going to make it a three (maybe four) channel mixer!
I have always wanted a cheap/small/ easy way to mix several sources.
My new plan...
-Use the existing phantom power circuit to power a third (or fourth) microphone.
-Add in two line input jacks.
-Add a passive "blend" control to mix the extra microphones (brought up to line level with the transformers) with the line level source.
So, I could run my regular rig. Patch the line outputs on the PMD671 to the inputs on this new box. Then mix in a third microphone (typically an omni) for a three microphone mix. I'd then run this signal (line in) to a DAT.
This way, I'd have my usual two microphone recording and then a three (or possibly four microphone) mix as well.
The blend contol could be a simple 10k pot (tied to ground on one side) that feeds the microphone signal (at line level) equally to the line outputs.
To me, a device like this would actually be useful.