Dave Grohl's great new documentary, Sound City, tells the story of the "dumpy" L.A. recording studio where a stunning number of rock worthies – including Neil Young, Fleetwood Mac, Tom Petty, Cheap Trick, Nirvana and Rage Against the Machine – made historic albums. It's also a burnt offering to the pretty much dead religion of pre-digital record-crafting – what Grohl calls "the human element" in rock.