After discovering that the Alpine CDA-7878 lacks the orange illumination lead that my CDA-7876 has I decided to check into "illumination" more.

Apparently all the "illumination" lead does is to dim the radio's buttons when the headlights are turned on. The buttons and dial are brighter when the lights are off and dimmer when the lights are on. Using the radio's "setup" feature, you can disable this dimming.

Do any aftermarket radios light up the radio buttons at night when the radio is OFF but the lights are ON? Does the stock radio work this way? The stock stereo on my '93 Prelude has lit up buttons when the lights are on and the radio is off. I don't remember whether or not I had that on the S2000 before I removed the stock radio.