Today, Robert Plant begins the third season of his podcast Digging Deep with Robert Plant on which he reflects on his storied career and shares the stories behind the music.  To coincide with the season premiere, Plant has announced a new career-spanning 2-CD set.  Due on October 2 from his own Es Paranza label, Digging Deep: Subterranea compiles 30 tracks on two CDs (or streaming/digital) from his solo body of work. Digging Deep: Subterranea will be the first 2-CD collection of the Led Zeppelin frontman’s solo works since 2003’s Sixty Six to…