... the power antenna line is only powered on when you switch to tuner mode, whereas the amp remote line is on the whole time the empeg is running ...

Check. I ordered an antenna booster that you plug the antenna into, which in turn plugs into the tuner module. It has a red wire that, AFAIK, I'd connect the power antenna wire to. If all goes well, I'll have an advertised 300% boost in signal strength (or something along those lines).

There is also a small hardware bug where some power antennas won't retract when you switch sources. This is easily fixed though.

Question: Could that also affect the antenna booster kicking in when I switch to the tuner?