I think the Audio Output options on this new Apple TV need work. They don't work in the same way as the old Apple TV (2nd Gen, 720p) that I have.
On the 2nd Gen ATV, I choose Automatic on the audio output, meaning that if Dolby Digital 5.1 is available, then that bitstream will be output to my A/V receiver. If it's just stereo, then PCM 2 channel is output. All good.
But on the 4th Gen ATV, if you select auto, it outputs PCM 7.1 channel to my A/V receiver, even if the program is 5.1 (example - NETFLIX app). Meaning the back surround speakers are silent. And there's no way to apply Post Processing in the A/V receiver to get the rear surround speakers working (like applying ProLogic IIx).
Even worse, if you select Dolby Surround as the permanent audio output option, then EVERYTHING outputs as 5.1 Dolby Digital into the A/V receiver, even your music, with only the front Left/Right speakers active, and the rest silent. Again, you cannot apply any post processing to the 2 channel music (Like ProLogic IIx Music) because it's in forced Dolby 5.1 mode. And of course it's a Dolby Digital re-code of your music, whether it is Apple Lossless or AAC.
They need to make the audio output options work like the older Apple TVs.
ie, in AUTO, if the signal is plain stereo, then only a 2.0 PCM signal should be output over HDMI.
If a Dolby Digital 5.1 signal is available on a movie, then it should only be 5.1 output, not Linear PCM 7.1 with silent rear speakers.
If a Dolby Digital Plus+ 7.1 signal is detected, then it should output Dolby Digital Plus+ 7.1 bitstream to the A/V receiver.
If the user wants multi channel linear PCM output over HDMI, then there needs to be more options to select that too.
Craig.