First off, don't short the output jacks of your amp with the antenna wire.
Antenna are designed to transmit or receive on higher radio frequencies.
Amplifier outputs are designed to output lower audio frequencies.
Theoretically I suppose and antenna connected to an amp output jack would be
outputting a low frequency, but not useful because of frequency and tuning of antenna.
In practical terms, all's you'd be doing is creating electrical noise. And if the antenna
touches something during this experiment, the output of the amp would be shorted to
whatever the antenna touched, possibly damaging the amp.
(That's the reason amp output cables are shielded and insulated).
Maybe somebody here will have a technologically deeper explaination for you.