candyman, I think for bluegrass this could work maybe. No drums, no other amps on stage (like guitar or keys) I am guessing.
You might could try posting your question over in the
Bluegrass forum too. And maybe send a PM to
Bob Knebel too. He's got a Coda I think.
Have you run a mic into your amp on stage before? I would be concerned about the mic squealing w/ feedback, depending on how high you want it to go, and where you (and the mic) are positioned relative to the amp.