[robodan]

Bose sells line array speakers that will happily work if placed behind a standard mic. They are using anti-feedback DSPs to cancel the audio loop this creates. They can be used in a speaker per performer setup.

What is weird is that they don't talk about this. There is a graphic on products that can do this that show the speaker behind the mic. That's it, no text at all. I think the moral of this story is that marketing is weirder than engineering...