Threads:
- https://www.talkbass.com/threads/compact-looper-with-midi-sync-advice.1322813/
- https://www.talkbass.com/attachments/screen-shot-2018-01-15-at-10-50-39-am-png.2876469/
- https://www.jazzguitar.be/forum/guitar-amps-gizmos/59519-loopers-midi-sync.html
- https://www.gearslutz.com/board/electronic-music-instruments-and-electronic-music-production/1100762-looper-midi-sync.html
Pigtronix Infinity Looper (seems to be the favorite):
- https://pigtronix.com/product/infinity-looper/
- https://www.reddit.com/r/guitarpedals/comments/6ggsgq/pigtronix_infinity_looper_roland_tr8_midi_clock/
- https://forum.fractalaudio.com/threads/infinity-looper-format-larger-sd-card.104993/
BOSS RC-30 (no MIDI sync, only there 'cause I have one):
- http://forum.mybeatbuddy.com/index.php?threads/need-help-w-my-beat-buddy-and-the-boss-rc-30-looper.1325/
- https://www.talkbass.com/threads/is-it-possible-to-sync-two-boss-rc-30-loopers.1291450/
- https://rolandcorp.com.au/blog/taking-control-of-your-loop-station (also, W.T.F. ???)
BOSS RC-300 & RC-505: