Or you could look at the professional audio sound reinforcement market. The latest release from sony is a stereo digital input speaker manager. Unfortunately I don't have all the specs but the short review says:
It provides audio processing and loudspeaker management functions. Programmed via a PC, up to 99 units can ber operated from a single PC com port making the {product} well suited for use at large venues requiring complex control.
Audio Technology, V2 I5

OK it doesn't really do 5.1 surround but there are a plethora of products which would do exactly what we want. But they wouldn't be an integral part of the empeg installation.
Unfortunately nothing much can happen until some sort of API comes out.

I'm not complaining or poking fun, and if anyone wants to put anything in their car, let them. I just want an empeg operated device.

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Murray 06000047