If by stock session you mean Mojave to Bakersfield, that is the only one that gives the control option. The other Mojave sessions bring you to cab mode with no option to choose.
ETA: I just started up all the built in sessions and they don't seem to have the sound issue, nor do the Maria's Pass sessions. It seems limited to Mojave and MWG. I don't know if that is of any help.
I would wait till the sound issues are cleared up with the SP1 hotfixes and such as I experience personally sound cutouts on any route, its not limited to just Mojave and MWG. Many others also experience this and with the 2 hotfixes out along with SP1, who knows which one fixed it/broke it/broke it again. I'm sure this sound issue will be addressed by N3V shortly in another hotfix, so until then not much we can do about this. For me at least going in cab and back out makes it work again until it cuts out again.
If its the built in TS12 sessions, there isnt much we can do about the control options.