hay there
setup your control room with at least one monitor and one headphone buss. assign these buses to your device outputs. Your interface should have at least 4 outs; l-R to your main amp and L-R to your headphone amp. I use an old stereo as my headphone amp cuz i can have independent volume, tone control.
On the output tab disconnect your stereo buss form any device. only connect devices in the control room tab.
In the preferences (VST - controlroom) check the option “use phones channel as preview channel” (3rd down).
Then in the keycommand section set uup a key to toggle it. (i usee the “=” key
Have fun