Larry, you are indeed The Man...
You were exactly correct. The Lectro guys concur with your comments about the impedance mismatch. And they are filing away the info about higher battery drain on the active preamp of the bass. They hadn't thought about that, but they definitely see where it would be an issue.
I'm now getting prices on the UM400 and the SMV series, although the SMV series are a lot more expensive and have waaay more features than I would ever need (We use the SMV and the SMQV for our lapel mice at church and they are awesome).
Also, I'm glad you mentioned the MI33 cable. Lectro recommended the MI39 cable, but upon further reading, I learned that the MI33 cable is more suitable for high-output instruments like my active Music Man (to Lectro's credit, I didn't tell them which instrument I was planning to use). That was a big help, too.
I so very much appreciate you taking the time to respond to this, Larry. I'm headed in the right direction now and I hope to have the UM in my hands before too long (after, of course, my account recovers from buying that EBS Fafner bass head from Ebay this morning. It kinda popped up a couple of days ago and I've wanted one of those for a very long time. Too good a deal to pass up.
Thanx again and take care, Larry.