Cubase 12 and UR816C DspMixFx

I cannot find a way to separate de headphone input from the main output knob and mute in relation with Cubase 12 Control Room controls
I have to use a separate headphone amplifier and route a monitor to it . Why I cannot use the headphone otput of the interface from Cubase 12 headphone and Main control as I did with MOTU traveller all this years?
Thank you in advance