You can connect the ssp600 12v trigger output to the a remote switcher,
when you turn on the ssp600, it will automatically connect the ssp600
front left and right channel to the power amp inputs, when the ssp600 is
turned off, the switcher will connect the anthem avm60 front left and
right channel to the power amp.
https://www.markertek.com/product/arx-rs-1/arx-rs-1-remote-switcher-stereo-xlr-balanced-remote-contr...
ssp600 -------->
Switcher -------> power amp
avm60 -------->
https://www.markertek.com/product/arx-rs-1/arx-rs-1-remote-switcher-stereo-xlr-balanced-remote-contr...
ssp600 -------->
Switcher -------> power amp
avm60 -------->