Has anyone tried cold cathodes for sound-responsive cases?

This sounds like a low-power fun case mod. The dimension of ur average Tek case should house a cathode. They typically are powered with a molex adapter which I presume can be routed appropriately. Big question is, could a usb power such a thing? It would look absolutely awesome if it could.

The sound responsive sensor will respond to any vibration if you dial it right, so clicking should make a flash.

Why mess with that instead of an LED controller?

Most PC cold cathode tubes and EL wire/panels run on a 12 volt source, USB supply 5 volts.
(PC Power supplys have a 5, 3.5 and a 12 volt rail).

You might need a separate battery pack for the cold cathode tubes.
Don’t forget you would also need a driver circuit for the lights