The four channels from the empeg are really two - Left and Right - just split to have different EQ on the front and rear. You're not playing a 4-channel file, so having front/back inputs doesn't really achieve much. I would expect to include a 5 channel parametric equaliser on each output so you could tune the outputs to your speakers. In other words, you wouldn't use the empeg's EQ for speaker-tuning.

I could include another channel of input, switchable (e.g. by a serial command), if it would achieve anything.

The time frame is very open - don't expect a product at all. I'm not a hardware developer and I would have to work through people who are 2000km away so it would be purely a hobby thing for now. This is as good a forum as any to judge what people think of my plans and to get new ideas.

My objective here is to put out a box with parallel goals to the empeg - a (nearly) fully configurable box that does everything you want. Most of the consumer solutions out there AFAICS have a very limited set of options because it's too expensive to give configurability and it's easier to give presets. I want a box that I can tweak and adjust to give me exactly the response I want.

I'm thinking of going up to 8 pairs because my brother has two dash-mounted tweeters that are a different height and forward-distance from his front midranges. Is this taking things too far, or not far enough?

(BTW, the empeg's DSP does not do this at all - it's only an EQ (AFAIK), albeit a highly tweaked one).

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