I've done a lot of searching the last few days and could not find anything, but I apologize if this problem has been posted before. I'm new to mixing and recording so please bear with me

I'm looking for a way to record my talkback mic so that signal recorded is 0.0 dB when talkback is off. Right now when I record my talkback mic in a DAW, it picks up positive signal regardless of if talkback is turned on or off. 

I use the RME Babyface, mix in TotalMix FX, record in ProTools 12.

Current setup in TotalMix:
Inputs:
AN 1 -> Booth Mic
AN 2 -> Talk 

Outputs:
Phones 1 -> AN 1/2
Main -> PH 3/4

I have speakers inside the booth to communicate. Headphones outside the booth to listen. Talkback input is set to AN 2.

Right now in ProTools, I have a stereo track with input AN 1/2. I suppose it makes sense that with this configuration I would not be getting what I want since my input is the direct analog signal. I have played around with the software playback and hardware output channels in TotalMix but... I have no idea what I'm doing.

How can I change my routing in TotalMix so that when talkback is off, the signal recorded in ProTools is 0.0 dB? Would it be more feasible to configure talkback in ProTools for this situation?

I do not need to keep the talkback mic in stereo with the booth mic.

Anything else you need to know about my setup, please ask. Thank you!

Edit (7/13): I ended up just configuring talkback in ProTools since I could not find a TotalMix solution.