what you'll want to do is have the actual output of the track go to 1-2 for the monitor controller
then you'll aux out sends 3-4 to the headphone amp, like you do now, and make volume/plugin/whatever changes on the aux send
gotcha
i have another question (all of my topics go off topic, this rules)
in cubase, i use pod farm in the input channel insert section, so that i can record a DI and the pod farm output from the DI at the same time
if i remove the pod farm plugin, i still have those recorded tracks of pod farm's output.
how will i do that in protools?