I haven't had the chance to try it out yet but if the Empeg is clever enough to allow the unit to be turned back on manually after power to its ACC wire is cut (ie key taken out of ignition) then that would be fine,

Please read this FAQ entry for details on how this works.

The Empeg's Yellow (Permanent 12v) and Orange (Ignition Sense) wires would be wrapped together and connected to a permanent 12v source along with the Kenwood's Yellow (Permanent 12v) wire too.

I recommend against this, as you will probably get amplifier pops if you do this.

Instead, I recommend connecting both of them properly (constant to constant, switched to switched).