It's taken me a couple of days to post this, but here's the link for the Nerdist Podcast - http://www.nerdist.com/2013/07/nerdist-podcast-josh-groban/.
It's quite long - almost 1½ hours. But be warned, DO NOT LISTEN if you are easily offended as there is (gasp!) profanity!
Personally, I really enjoyed it, but I know there will be many fans that won't, so don't say you haven't been warned.