Yes, I realize now that I am dealing with a ground loop. I apologize for not looking it up first so that I would know the correct term and not have wasted your time.

Matthew, changing the volume on the empeg does not affect the distortion I'm hearing.

And yes, the distortion only happens when the CD player is in AUX IN mode, which means it's empeg only. AM/FM and CD all sound normal.

I believe the source of the problem to be that the wiring harness I scrounged up for the empeg did not actually have a ground wire, and so I had to send the empeg's ground elsewhere (specifically to the ground on the CD player's harness).

This will be rectified as soon as I can find a new Honda standard wiring harness. And while I'm in the dash again, I also plan to reroute the RCA cables coming from the empeg, as they appear to be pinched between the CD player and unkown innards of the car. Just to be safe.

Thanks for your help, guys. I should be able to let you know by tomorrow how things worked out.