I would take Mark up on his offer because it'd be a cool road trip and good to see him again, but time prohibits. And in a last ditch effort to find this "easy" solution, I followed sein's link to "the other forum", which I tend to forget about.

W210 E-class amp audio input wires, 96-00 and 00-02
W210 E-class control wires, 00-02, confirmed by the apparently well known "Steve".
The install of the original requestor of the control wire info, who seems to know what he's doing.

This brings up another question. Apparently there are no switched 12V (ignition sense?), no headlight sense, and no dimmer sense wires. Kind of makes sense as the headunit amp keeps playing after I turn off the key, stopping when I take it out (annoying, but apparently stops when I open the door). Or maybe they're controled by CANBUS.

Can I get by using 12V constant power, ground, and remote amp turn on? I always pull the empeg out, so no worry of drained battery?

By the time I add a second head unit (ASAP) I'll probably have the amp and speakers replaced... if I had half a clue how to choose the proper materials for the job.

Thanks for your patience with my ramble.