Updating my audio collection has introduced a few new issues into the wrench. Adding
multi-channel audio has proven to be a little problematic.
- ReplainGain support for multi-channel audio is lacking in Fedora. I've poked one
upstream about it. 
- Downmixing multi-channel audio to stereo results in poor output out of the box
with Fedora defaults. The rear channels are basically dropped. Attempting to use a
PulseAudio virtual surround sink results in muddy, soft audio. Using a remap sink to
send rear channels to their respective front channels results in clear, soft audio.
No normalization appears to happen.
My multi-channel setup: Kodi -> HDMI -> 5.1 receiver -> speakers
My stereo setup: Rhythmbox -> analog jack -> speakers
FFmpeg and other audio processing libraries and players (including Kodi) have proper
downmixing that includes normalization with their defaults. Even my Pixel 3 appears
to do it right if I send a 5.1 track to it and play it out of its stereo speakers
when I played a 5.1 track and its stereo duplicate track back-to-back. I find it a
little disappointing that PulseAudio isn't doing it and would love to fix it.
Who would be the best candidate to go after supporting a proper downmix +
normalization path? PulseAudio? Gnome? Rhythmbox?
If you haven't experienced a multi-channel audio track I highly recommend it.