Is pirating music immoral? Why or why not?

In one way I think it must be immoral because it involves gaining the unearned, but there have been (granted I know little of the music industry) many claims that illegal file sharing has actually been good for the music industry in a number of ways. There have also been arguments that it is not technically theft because it involves copying information instead of physically taking it from the owner i.e. the original owner (and creator) has not lost the music even after you have copied it, but this argument seems shoddy by its concrete bound concept of theft and ownership. Simply put, to me, it feels immoral, but I have trouble conceptualizing exactly why.