[Luke M]

@thefrog thx.

Will add it to list of known issues on Post #1

Since you're keeping track of issues, note these audio problems:
1. 7.1 PCM doesn't work correctly (side & rear channels reversed). Select 5.1 audio in Kodi settings.
2. 2-channel PCM is transcoded to DD/DD+ (can be avoided by selecting 5.1 "fixed" audio output, instead of the default "optimized").

Note: if using 5.1 fixed (as opposed to passthrough), Kodi will degrade the quality of AC3 audio by default. Can be overridden with advancedsettings.xml file. 

Is this still true with the latest firmware?
What needs to be written in the xml?

Code:

<advancedsettings>
<audio>
  <!-- Whether to use Dynamic Range Compression (DRC) on AC3 streams. 1.0 is "full" compression, as defined by the audio track's metadata, which is recommended for "basic" sound systems such as the internal speakers on a TV. 0.0 is no compression at all, which is recommended for people with nice multi-speaker sound systems. -1.0 (default) defaults to whatever ffmpeg uses, which is currently the same as 1.0. This has no effect if passthrough is enabled for AC3. -->
  <applydrc>0.0</applydrc>
</audio>
</advancedsettings>

If you set up ADB (which I recommend), you can write it to the FireTV like this:

Code:

adb push advancedsettings.xml /storage/sdcard0/Android/data/org.xbmc.kodi/files/.kodi/userdata