When a digital audio cable is to be used? I have noted there is audio cable with RCA jack labeled with "Digital Audio", looked alike a regular analog audio cable. What is the difference? Can it be used as a replacement to regular analog audio cable without adverse effect?
The simple answer is: there is no physical difference in the cables. You can use a "digital" coax cable for analog audio with no effect at all.
Digital audio is used for devices that output a digital audio stream (PCM, Dolby Digital, dts, etc.). Most DVD players, for example, have an optical out and/or a digital coax out (which is what you're referring to) that both serve the same purpose but use different cables.