Bose Interface for aftermarket amps and subs...etc

[PewterPower]

NSXer: Would one of these interfaces give my aftermarket amp/system the ability to continue playing after the ignition key was removed ? My stereo installer does not know how to maintain this ability after installing the aftermarket amp behind the factory amp ....any help you can provide would be great.

As of now, the only speakers that remain playing are the two in the rear of the vehicle...used primarily for Onstar. They are the only ones still powered purely from the factory amp.