12V relays are cheap and easy to come by from electrical suppliers, and can even be bought with a nice screw down base, with a legend for how to connect the relay. mine cost me 15 bucks, for a 4 pole, double throw relay, that'll do 10 amps on each pole, LOTS of power.

Uh huh. I checked out BCAE and it all makes more than sense (what an awesome site!). I'll just pick up a standard 4/5 pin 30A relay. With the right fusing things should go just fine. I'm also throwing in a separate switch to turn my sub amp on/off; it'll fit nicely in the custom panel (also to be made) leftover in the 1/2 DIN space the EQ has created. Good times...