The Avantis does not have the ability to automatically gain compensate when two or more systems are connected together. The DLive has this ability, but that is the only currently offered A&H system that does.
Obviously both systems will have digital trim adjustments and it’s standard practice to only adjust the trim setting on linked consoles once the preamp gain has been properly set. By adjusting the digital trim setting, you are only affecting that console’s gain structure. Local digital trim will not affect any of the linked console’s gain structure.