This article is in fine shape. I can't think why it's been waiting since December for consideration. A few drafting points before I go further with the review: 
 *Lead 
 **You mention in the lead that the piece is dedicated to the composer's mother, but you don't mention it in the main text. There should be nothing in the lead that isn't in the main text (see Wikipedia:Manual of Style/Lead section). And is the dedication of a piece of enough importance to be singled out for mention in the lead? 
 **"becomes sped up" – I can't find a modern example of "sped" for the expected "speeded" as a part participle in The Oxford English Dictionary. There are plenty of 17th century examples quoted in the OED, and I have an idea it might still pass muster in American usage, but not in modern English. 
 **reference format – see ref 2: we are enjoined to put refs after, not before, punctuation marks. 
 *Composition history 
 **"Morrison" – at his first mention in the main text, Morrison needs both given name and surname and a blue link, 
 **ENO and Coliseum – blue link at first mention in main text 
 *Music 
 **"Obligato" – I think I have seen this spelling before, but "obbligato" is usual, and I believe correct. 
 **"slow-motion Mahler" – not a comment on your prose, but I must pause here to recover from the thought of Mahler being protracted any further than his interminable self. 
 *Synopsis 
 **"to fix on creating…" – not entirely clear what this means – is it "to decide to create"? 
 **There's another unexpected "sped" here, which needs to be "speeded" if I correctly read the OED. 
 *References 
 **WP's practice (Wikipedia:Manual of Style/Capital letters#All caps is to reduce newpaper headlines from all capitals – as in your Murray quote – to upper and lower case. 
 The criteria for GA are not so strict that any of the above would disqualify the article, but you may, nonetheless, wish to consider them before we proceed further. –