Most always when you go to connect two pieces of electronics together for Analog Audio you will find yourself using RCA cables.  These are the ubiquitous cables with a round plug, about the size of a pencil eraser, consisting of a metal ring around a single pin.  That pin fits into the single hole of a matching, RCA socket, and the metal ring of the plug slides over the barrel of that socket to complete the connection.  For a Stereo connection, you would use two such RCA cables.

But PROFESSIONAL Audio gear frequently uses much cooler-looking cables, with a bigger plug (still round) containing THREE pins.  These are XLR Analog Audio cables -- also called Balanced cables.  Again, for a Stereo connection, you would use two of them.

Higher end Home Theater gear will frequently offer the option of using either RCA or XLR cables for your Analog Audio connections.  The XLR choice is undeniably the Cooler choice!  But if you've ever wondered whether there's any OTHER reason to use XLR cabling, this post is for you!