Music in the age of mechanical reproduction

Since class today, I've been thinking a lot about Kurt's choice of an LP(/CD/ringtone) as an example of the ways in which art can be reproduced into worthlessness, and the ways in which music speaks to Benjamin's framework, specifically the notion of "aura."

First off, where IS the aura of a piece of music, or what, really, is the work of art? I suppose it's a somewhat rockist idea, but it took me a while to shake my gut-level equation of composer and performer and realize that that characterization is (both synchronically and diachronically speaking) wholly inaccurate more often than not. Many modern pop stars obviously don't write their own material, to say nothing of performers in orchestras throughout history. So if artists or composers create works of art to be performed by others, and have historically tended to do so, isn't that a type of aural reproduction long before the technology of film and cinema brought it into the visual realm? Granted, it's not mechanical for two different orchestras to play the same piece. But they're reading copies of the same music with the same notes, dynamic markings, etc. Does it really make a difference if these copies were transcribed by hand or by a Xerox machine? This brought me back in a roundabout way to Benjamin's comments on stage/cinema and his claim that "there is indeed no greater contrast than that of the stage play to a work of art that is completely subject to or, like the film, founded in, mechanical reproduction" (in section IX); I think we could set up a similar relationship between live musical performance and recorded music. But really, aren't plays and pieces of music made to be reproduced?

As I said above, what's at the heart of this tension clearly is the question of what exactly is the work of art. Is it the play/composition or is it the performance? I'm inclined to say "both," but Benjamin's commentary only seems to deal with the performance. So, am I off base here? If not, what of the aura of the piece, musical or theatrical, itself? If the aura of a work of art is based on "its presence in time and space" (II), does the aura of the artistic composition, as opposed to the artistic performance, survive mechanical reproduction intact because it's wherever it's being experienced by an audience?