Video from Mac to Apple TV, audio to Airport Express I want to output video from my rMBP to my Apple TV but send the audio to AirPort Express connected to my sound system.

I have tried every way imaginable to accomplish this, and nothing seems to work. All links in the chain have updated software &amp; firmware. Hardware is the following; rMBP Late 2012, Current Gen ATV, Current Gen APE. All running on rock solid WiFi.

If I start by sending video, it quits when I select the APE audio source, if I start by sending audio, it stops sending when I enable mirroring on the Mac.  

I have tried under System Preferences on the Mac to have the system audio routed to the AirPort Express, but no luck. I have tried routing the audio to the APE from the ATV's prefs, also a no go.

Strangely this works like a champ from an iOS device, not from my Mac. I can send the video from the Mac to the ATV and send the audio to APE via Airfoil, but there is a noticeable lip sync issue, so that is not an option.

I read a Lex Friedman article on MacWorld touting the ability to do this.
You'll love this: On Apple Tv go to Settings → Airplay and pick your Express under Speakers. Now stream away to your Apple Tv. Everything is in sync and all, at least using Beamer (which is much superior to screen mirroring if you are watching movies).

Edit: sorry you already tried this? Works perfectly here.