How to AirPlay 5.1 Surround Sound via Apple TV 4/3/2?

1. Does AirPlay Support 5.1 Surround Sound?

The answer to this question is absolutely positive. At present, AirPlay supports and only supports up to 5.1 surround sound (Dolby Digital 5.1 surround sound pass-through, already decoded). Though Apple TV 4 is now able to output 7.1 surround sound yet only via HDMI, it is still nebulous whether there will be an AirPlay revision that adds 7.1 surround sound support to it.

2. Basic Settings to AirPlay 5.1 Surround Sound via Apple TV?

Then, first thing first, let's get some knowledge about basic settings for AirPlay 5.1 Surround Sound via Apple TV 4/3/2.
Go into the settings on your Apple TV and make sure Dolby Digital is set to "on" instead of "auto", then you'd better encode your music videos to Apple Lossless (ALAC). To watch movies with AC-3 5.1 surround sound on Apple TV, the media file shall be placed in both “Advanced Audio Coding (AAC) stereo” and “AC-3 surround sound” audio tracks at same sampling rate of about 48kHZ. Aside from that, it is suggested that the audio files be prepared adhering to the following points:

● AAC audio track should be open and put in ahead of AC-3 (DD5.1)
● AC-3 (DD5.1) audio track shall be set "off" as default.
● Proper MPEG-4 / ISO standard shall be applied to the AC-3 (DD5.1) audio track
The surround sound field would be ported out via HDMI or optical audio-out. Now you can go to the Settings > Audio > Dolby Digital Out and check "on" the DDO to complete a perfect connection.

With 5KPlayer installed on your Mac/Windows PC, you can directly open a 4K movie file with 5.1 surround sound or a pure 5.1 audio track stored in the local disc, or open your Netflix/HBO GO, and AirPlay the 5.1 surround sound smoothly to your amp connected Apple TV.

3. Why Can't We AirPlay 5.1 Surround Sound via Apple TV 4/3/2?

If you are using Apple TV to achieve 5.1 surround sound AirPlay, you are well aware that there are three connections: V/A AirPlay sender to Apple TV (key: AirPlay requirements), Apple TV to HDTV, Apple TV to AMP (key: HDMI/optical-audio port). Thus problems may exist in those connections and devices, preventing us from AirPlay 5.1 Surround sound. Let's sort them out:
1. AirPlay 5.1 Surround Sound sender:
You are using a Third Party App that does not natively support 5.1 surround sound let alone 5.1 surround AirPlay. (Make sure it does support 5.1 surround sound before AirPlay)
Also, make sure that you are not using AirPlay mirroring, which puts your whole OS and display into AirPlay and stream the re-encoded file instead of the raw stream.
2. AirPlay supported formats:
You attempt to AirPlay 5.1 audio tracks that contained in AirPlay not-supported formats.
FYI, AirPlay only supports videos in MP4, MOV, M4V, and audio in MP3/AAC, and Videos app on iOS devices only plays with ACC stereo track. It would be better if you encode the audio to ALAC.
3. AirPlay 5.1 Surround Sound receiver:
If you are using AirPlay compatible speakers/AMPs for audio-only 5.1 surround sound AirPlay, it seems that there won't be any problem to get a seamless connection. However, if you are using Apple TV as the receiver, esp. Apple TV 4, you should be alert since there is no optical-audio port in Apple TV 4 to connect your optical audio-in AMP. You may want to stay with your old Apple TV 3/2, purchase an AirPort Express with optical audio output, or purchase a HDMI AMP. FYI, AppleTV doesn't support DTS audio, so be sure that your audio is encoded in DD5.1.

Yet still, it's worth notice that your HDTV itself might have optical audio port! Check that out first! If it does, you can connect the amp with your TV directly for 5.1 surround sound AirPlay, but you may also easily fall into a mis-assumption -- porting HDMI to your TV and hoping to take optical from TV to your AMP. That's just not gonna happen, since some TVs don't support DD and/or DTS passthrough from HDMI to optical. Therefore, you may need to decode the Dolby Digital audio to multichannel PCM.

4. Must-Haves for 5.1 Surround Sound AirPlay via Apple TV 4?

Here, to tackle each possible obstacles on the way of 5.1 Surround Sound AirPlay, we list out serveral necessities that guarantee 100% success rate in 5.1 surround sound AirPlay. You'll need:
A professional free 5.1 Surround Sound AirPlay sender - 5KPlayer - efficient free AirPlay sender you can ever get to collect all the movies music you like; 5KPlayer can directly convert the audio/video into MP3 format for AirPlay.
A video/audio file converter - in case we need to convert the 5.1 audio track to some rare codec/format;
A proper 5.1 Surround Sound AirPlay receiver:
For your Apple TV 4 AMPs, you have two choices:
*A HDMI switching Hi-Fi receiver
*Apple's AirPort Express wireless appliance, which has optical audio output for your amp.

5KPlayer is an AirPlay built-in wireless 5.1 Surround Sound AirPlay sender. It enables your Mac and Windows PC to play back 7.1 surround sound and stream 5.1 surround sound directly to Mac/PC surrournd sound speakers without Apple TV. As an AirPlay sender, 5KPlayer can
*AirPlay 5.1 Surround sound A/V files to Apple TV with amplifier (video-audio);
*AirPlay 5.1 Surround sound to AirPlay compatible wireless audio amplifiers (audio-only);
*AirPlay 5.1 Surround sound to Apple's AirPort Express wireless appliance;
As an AirPlay receiver, 5KPlayer also supports iOS 9 AirPlay, chromecast AirPlay and music app AirPlay like YouTube, Spotify, Soundcloud etc.

How to AirPlay 5.1 Surround Sound with 5KPlayer?

Given that all the settings and preparations are rectified, we can now AirPlay 5.1 surround sound smoothly from 5KPlayer installed Mac/Windows to your Apple TV.