I could have Empeg feed the optional AUX inputs of a Kenwood (or other) head unit

Two ways you can go here. Have the empeg feed the Kenwood, or have the Kenwood feed the empeg.

Empeg feeds Kenwood: Pro: The Kenwood works when the empeg is not installed. Con: You don't get to use the empeg's 20-band parametric equalizer when playing CDs from the Kenwood.

Kenwood feeds empeg: Pro: You get the empeg's equalizer with the Kenwood. Con: No empeg, no sound.

I'm building my new system with the Sony switch, and I think it is the way to go. I will be doing it with CD player feeding empeg with one small twist: I am adding a relay to the control line of the Sony switch so that signal out to the amplifiers *always* comes from the empeg as long as the empeg is in the dash and turned on; otherwise it comes from the CD player. This is to accommodate having both the CD player and the empeg on, with the CD player feeding the Aux Inputs of the empeg so I can use the empeg's equalizer.

tanstaafl.

"There Ain't No Such Thing As A Free Lunch"