Bose Interface for aftermarket amps and subs...etc

[PewterPower]

I think that's the issue....determining the power-feed for the factory amp. My installer says that he cannot locate one.....says this system is just like the one in some Cadillacs.

Because the power feed for my aftermarket amp is not the same source as the factory system....I lose that when I turn off the ignition. I don't want to direct-wire it and be responsible to turn it off each time but would like to enjoy the feature where it stays on until the doors are opened if possible.....

Any suggestions on where I might go to investigate this further ? Maybe the dealer ?