I tried the Shure PG42-USB on my wife's 2013 iMac which is running Mountain Lion. The mic works fine on that 2013 machine with QuickTime 10.2.
Yet, the same mic does not work with the Mavericks OS. Any ideas?
As of February 2014: There appears to be discussion on the web that indicate there could be a problem on Apple's side. Recent Apple computers (late 2013 onward) that use the Mavericks O.S. apparently have issues with certain USB devices.
As the Shure X2u and the PG42-USB mic are hardware only, and do not require special firmware or software on the computer, this issue has to be resolved by Apple and their O.S. software designers.