I studied for and gained a BA Hons in Music Industry Management & Popular Music (Sociology of Music), which concentrated on all aspects of the Music Industry, such as Recording Contracts, Publishing/Intellectual Property Law, Touring, Management, Merchandising etc and worked in Music Copyright/Publishing for 7 years.
The Donald Passman book was seen as the "Bible" for our course and certainly proved to be a wealth of knowledge, exploring just about every conceivable aspect of the music industry. I am sure it has been updated a few times since the copy I used, which was bought in about 1998, so it obviously had no Digital Music section, but considering how large a part this now plays in the Music Industry, I am sure it will be updated to include all of what is relevant to this area.
The book is/was written from a majority US perspective (don't know if the updated versions still are), so I felt in some instances certainly Copyright/Intellectually Property Law, Publishing sections referred more to ASCAP, Harry Fox, BMI, SESAC than their UK equivalents, which wasn't always helpful for my studies.
Read this a few years ago http://www.amazon.com/The-Mansion-Hill- ... 0679743774
and it was a very good behind the scenes read of the US Record Industry mainly from the 60's to the 80's, taken from the point of view of record labels, band managers, record company exec's, artists etc.