“Mr. Guralnick’s e-book project is a particularly ambitious example of what seems be a growing trend in the publishing world. As the technology for adding ‘enhanced content’ like music, video and documents to the electronic versions of books advances, publishers are incorporating more of that material into work about popular music, whether critical assessments like Mr. Guralnick’s or the autobiographies and memoirs written by musicians…
“Mr. Guralnick, of course, doesn’t control any song copyrights, but he did preserve tapes of many of his interviews, and excerpts have been inserted into the e-book versions of Feel Like Going Home and Lost Highway. They provide both context and atmosphere: In an interview with Muddy Waters at his Chicago home, his grandchildren can be heard scampering around in the background, and during a conversation with the blues songwriter and producer Willie Dixon, conducted at the business offices of Chess Records, the telephone is constantly ringing.”
– Music Writer’s Opus, Now With Sound: Video and Audio Being Added to Peter Guralnick’s Books (Larry Rohter, NYT)
RockCritics.com 
Thanks for that, and speaking of electrically enhanced Americana, here’s a pretty remarkable new piece by John Jeremiah Sullivan–starts out like it all might be a rehash for the noobs (material like this requires a balancing act for old hands and new eyes, in still-relatively-mass publications, anyway)
Also: from Best Music Writing, the ILX thread where Scott Seward put up the Sullivan link, and I first saw it, a couple of follow-ups:
i e-mailed greil m. to rave about this and he said i wouldn’t believe the stuff that they cut out of it. so i’m hoping their is an unabridged version in some future collection of his stuff.
― scott seward, Sunday, April 13, 2014 12:58 PM (2 hrs ago)
haven’t read the times story yet but strongo linked to this thing (Sullivan) wrote for the oxford american earlier this year, it’s pretty great – http://www.oxfordamerican.org/articles/2014/feb/18/chop-upbeat/
― balls, Sunday, April 13, 2014 2:00 PM (1 hour ago) Bookmark Flag Post Permalink
Also (courtesy Luc Sante): some backstory, by Michael Hall, 2002 CE:
http://www.texasmonthly.com/content/mack-mccormick-still-has-blues
Note that Sullivan’s email address is at the end of his piece