the "unmod" removes the stereo mini and adds minixlr output connectors.
is't this the same principle?
http://www.soundprofessionals.com/cgi-bin/gold/category.cgi?category=250&item=SP-XLRM-MINI-2&type=store
You have to run the battery box in front of that. I might be wrong here (and I prolly am...) but since the signal goes from XLR to 1/8' - it can no longer push phantom power through to the mics- Phantom power, AFAIK, needs XLR the entire way through.
The "unmod" that is being discussed is to take off the 1/8" connector and put an XLR connector (and power conditioner, depending on the unmod) on the ends of the mics so they plug directly into the XLR inputs of the UA-5, and accept phantom power for the mics. This "unmod" actually turns the AT mics from SP into "stock" AT mics (for lack of better terms), and makes them no longer connected to each other in wiring terms. A different variety of the unmod gives you the flexibility to either run off phantom power or the battery box.
Marc can prolly describe this in better terms than I am using.