Generally speaking you wouldn't want to do this as you can run into some issues. However, if you're using Mac OS X you can create an Aggregate Device in Audio MIDI Setup and use the Aggregate Device inside of Studio One. But keep in mind you can potentially run into issues with using and Aggregate Device and isn't supported. A better option may be to use something like a Monitor Station V2 or Central Station if you need a monitor controller and talkback option.