i would just run the remote wire to a switch to turn off your amp. this should work fine just remember to turn down the volume on the deck before you turn the amp on if you are already listening to music (some amps turning them on with the music cranked do not like this at all, most its ok, but i'd be safe anyway).
this is actually exactly what I did. I hide the switch in my cig. tray so whenever my girl gets in the car or I pull into the neighborhood or don't want to piss of cops at a light I open the tray and flick the switch.
I spliced the remote turn on wire and extended it with some wire in the tray from behind, there is a little notch on the top so the wire slips right through and just hooked one end on one end of the switch and the other to the other and then yea. you'd have to see it I guess
Guess Im lucky.
I wired the remote directly into an open accesory fuse with a connector. The amp has a delay so when the car is turned on it gradually builds up, and if a copper happens to show up while my tunes are a 'little' loud, I have one of those attention buttons on the deck that drops the volume instantaneously.