Steps to repro:
1. Open the attached project and the scene
2. Press play
3. Each button presents a test case:
1.) The ideal approach:

Start a stream by opening a WWW request, set the audio source to loop -> does not not work because only the last pieces of the WWW buffer seem to be looped

2.) The first workaround:

Stream the audio by WWW. If the source got ended (IsPlaying is false), restart the source -> restarts the sound, but leads to a hearable break in audio

3.) the second workaround: stream the clip by WWW and play, for "pre-buffer" stream another WWW with the same clip. swap clips once the old clip got ended -> same as case 2 - noticable gap in playback