I have an LC III that boots and runs normally, but the internal speaker doesn't work. Well, at least I thought it didn't at first.
External audio works; I heard the startup chime, quacks, and wild eeps through headphones. By accident I was pushing the headphone jack while turning it back on...
I'm pleased to report there is now a fix for audio glitching when using a Carrera040 accelerator card (original or clone) in an SE/30, thanks to a revised Control Panel from @Bolle and GeekDot. I have uploaded it to the Macintosh Garden here...