Pirate Audio 3W pinout - ground required on pin 9 for stability

[TechWilk]

Despite what is currently listed online, I'm struggling to keep my Pirate Audio 3W hat stable without connecting Pin 9 to ground, which isn't shown as connected on the site. If I leave it disconnected, my Pi halts and reboots after a few seconds of playing audio.

I've tried swapping the pi, sd card and reflashed with the latest bullseye to no avail, but connecting pin 9 solves things, so I have come to the conclusion that it is a required pin.

https://pinout.xyz/pinout/pirate_audio_3w_amp

Thanks for your work cataloguing all of this!