Working on vintage hardware, with a vintage set of speakers (yes, yes... wrong brand.. I know...) can cause no end of stress. Recently I set up the Amiga 1200 on my desk and used my trusty old AppleDesign Powered Speakers. I'd had issues with these in the past: One channel was soft and the balance was even at 75% left. After opening them up, I re-soldered a few dry joints and all worked well again!
I was nothing short of horrified when I heard the first beep from the Amiga. It only came through one channel. I checked the cables, the balance and jiggled everything... but to no avail. Further system sounds also failed to be broadcast over stereo.
Well... it turns out that system sounds are mono! Don't ever expect the base Amiga OS 3.9 to send sounds over both channels... as much as you mash the keyboard to make the actual beep occur!
It also turns out that I'm not the only person who has noticed this.