Scott Dorsey wrote:

DI transformers are high-ratio. This means they tend to have poorer
high end and are more expensive for the same performance than a 1:1
transformer.

Thanks... that's probaby something I will learn in the Sound
Reinforcement Handbook, no?

It's really not the right tool for the job. Try the Ebtech Hum
Eliminator on the cheap end, or the Jensen isolation boxes on the
expensive end.
--scott

The hum eliminator seems like a good thing to have around generally,
even if I don't use it for this.

Thanks again for your help, Scott.