tlh

well I went down to the garage for you with my cane

You are correct with the above post by toggling that bottom right hand switch you control what unit or both that will play in headset or thru speakers. The left side push button scolls thru each unit to be on or off or on at same time.
i prefer to ride with my xm thru the speakers and cb unit thru the headsets. I'm not comfortable with everything in headsets as I want to be aware of noises around me ( car, truck, kids, horns, etc.)
Hope this helps.
Stan aka NJF6Cowboy