As many of you know, the HBO Now and Showtime Anytime app still do not support Dolby 5.1 audio.

You may also know that the latest Amazon apk pulled from Sony TVs supports Dolby 5.1.

Today, HBO was added to the many Amazon "channels" you can add to your prime subscription. I am happy to confirm that if you use this method to access HBO, Dolby 5.1 audio is output. I tested Showtime as well and this works too.