A lot of aftermarket head units (and presumably any factory unit that's used on cars with power antennas) have a power antenna wire, that works basically like an amp remote turn-on wire, but instead of turning on with the head unit, it turns on with the tuner.

I don't remember anything mentioning the Empeg having a power antenna lead. Your best alternative might be to wire up a conveniently located switch that will allow you to raise and lower your antenna at will. Yes, it's an extra step, but it's probably more aesthetically pleasing than leaving your antenna up all the time.

Bill