This was a topic back in August, closed but not resolved as far as I can tell.
I want to play sound on both the TV and on an airplay speaker. When I ask the ATV to play sound on the TV and on a separate speaker it stops the sound on the TV and only plays on the airplay speaker. I know some apps on the ATV prevent sending sound to airplay speakers but the Channels App seems to do the reverse. Any fix for this?