The remote wire from the amp usually gets tied into the power antenna lead coming from the deck... This way, when the radio is on, regardless of ignition, the amp is also turned on. Without that power antenna wire though, the ignition switch "ACC" position sounds like a good workaround... But I can see the problem... Bummer. You can take the trailer way out and have a switch up front for manual control.

Don't some amps have sensing circuitry now that detect voltage across the speaker leads and automatically engages? I haven't been following trends in audio for a while... But I will be again down the road for the X. I'm in no rush for that just yet.