Thanks to all for your responses.
Ric, I did try running the EDB to the regular input (not via return loop) after talking with Rick at AI. This was using regular 1/4" cable. I set the EQ controls on both preamp and Coda flat. Put the gain and volume controls on the Coda at 12 o'clock, then used the gain and master volume on the EDB to manage the volume. In this particular bar, on this particular night (it's outside under a portico in Florida) it sounded really good. Nice and fat low end; mid and treble very clear. I needed to tweak the volume up once, and I reduced the "presence" setting on the EDB to reduce a little bit of boomy sound after that.
I'm continuing to learn about these preamps. As soon as I touch one of the EQ knobs I'm in a different world; not to mention turning two at the same time! My principal goal is to have volume control at the mic stand. I previously tried the FDeck for the same purpose, but it didn't work so well.
The guitar player suggested I try the XLR, so I thought I would ask you guys first to be sure it would not break anything.