The verdict for indie developers (not using Unity/Unreal) seems: just bite the bullet and license FMOD (or Wwise or any of the popular proprietary audio engies).
I was actually searching for a good open-source audio library to use, and found out that my options aren't that good. SoLoud is a pain in the ass to install and integrate into an existing codebase, and OpenAL doesn't have any good implementations available (either proprietary or LGPL). I'm now just using a simple single-header audio library in cute_headers (https://github.com/RandyGaul/cute_headers/blob/master/cute_s...), but will probably switch to MiniAudio once the high-level API is finished (https://github.com/mackron/miniaudio/issues/196)
I was actually searching for a good open-source audio library to use, and found out that my options aren't that good. SoLoud is a pain in the ass to install and integrate into an existing codebase, and OpenAL doesn't have any good implementations available (either proprietary or LGPL). I'm now just using a simple single-header audio library in cute_headers (https://github.com/RandyGaul/cute_headers/blob/master/cute_s...), but will probably switch to MiniAudio once the high-level API is finished (https://github.com/mackron/miniaudio/issues/196)