All this time... across two cars, and it was the AMP!!!!

I've pulled my hair out wiring and RE-wiring everything, buying every doo-dad out there and every trick in the book. Finally tonight I ran to Circuit City, bought a new amp, swapped the two and my engine whine was gone! The grounds were fine, the routing was fine, the empeg was fine, the alternator was fine and the wires were fine...

Finally, my two favorite toys - the WRX and the empeg, can be enjoyed together!