Hi,
i got the same Problem as described above, my Cinema Display looses sound like every 5-10 minutes. Unplugging and Plugging in again resolves the Problem, but only for a shot time. The Update above doesn't help, can't install it cause its not "needed". When it looses the Sound it starts playing it on my MB even if its closed.
I got an mid 2011 MB Air 13" with OS X and an 27" Cinema Display.
Hope u can help me.
MacBook Air (13-inch Mid 2011), OS X Mavericks (10.9.4)