I don't like the word cover.
In any other genre, when an artist performs the music of another artist, it's not a cover, it's simply a performance. you dig?
Nevertheless, Those Who Dig was at the Newport Folk Festival last year watching a set from David Rawlings and Gillian Welch. They concluded their time by Performing a tune made famous by Johnny Cash and his wife June Carter; Jackson. I was immediately struck by this performance and have been pondering the nature of the cover, and what makes them successful, ever since.
As I recently mentioned, Music is melody, harmony, texture, and rhythm. All of these elements of music are fair game for change in a good cover. Furthermore, an exact recreation is rarely exciting or worth listening to. For instance, there are people who own the soundtrack to the movie Walk the Line where Joaquin Phoenix recreates recordings by Johnny Cash. This was great for the movie, utterly dumb as a record, and unforgivable when people purchase Joaquin Phoenix's renditions without presumably knowing the original recordings.
But I digress.
The art of the cover is a re-contextualization of a piece of music already known to the listener that is infused with the style, voice, and subtlety of the new artist. I really enjoy it when artists manage to walk the line (pun intended) between genre's, and introduce fans to new music and new artists.
I have been recently enamored with Chris Thile's new group, The Punch Brothers, and their virtuosic re-envisioning of Radiohead's Packt Liked Sardines in a Crushed Tin Box. I could dissect this performance for pages, but I'll leave that for another time.