All of the badly-designed ones and none of the well-designed ones :) Often you'll see audio equipment with LED-biased voltage amps where the LEDs have some opa

All of the badly-designed ones and none of the well-designed ones :) Often you'll see audio equipment with LED-biased voltage amps where the LEDs have some opaque glop slathered on them so they don't make popping sounds under bright lights, and to a lesser extent so multiple channels inside the same box are optically coupled, which is a concern. LEDs are photovoltaic like any other semiconductor but for obvious reasons they are not sold in opaque packages. You could probably find devices that are disturbed by loud sounds and physical shock, because ceramic capacitors are microphonic.