Problems with Studio LCD & ball speakers

[Eagle]

Greetings, all.

Some of you may recall the problems I have been having with my 15" 
Studio LCD.  Recently my wife started complaining that the sound was 
not working on our Cube -- ball speakers hooked up to the Studio LCD.

To update you on the Studio LCD thing, Apple replaced my display -- 
with either a "new new" one or a "new refurbished" one, I'm not sure 
which.  (And actually I think it is my same old Studio LCD!!!  I say 
this because there was some "goop" on the plastic on the top right 
corner of the display, and the replacement has the same "goop" up 
there.  I could never be bothered to clean it off because unless you're 
very close it's not noticeable.)

I'm wondering if the replacement LCD is having problems with the USB 
hub, because as I listen to iTunes now, the sound is cutting in-and-out 
somewhat -- but I'm also ripping the CD the MP3s of which I am 
listening to at the moment so perhaps that is a factor.  I have found 
that if the speakers are not functioning, simply disconnecting and 
reconnecting them to the Studio LCD fixes the problem.

Anybody else ever seen problems like this?

BTW - OS is Jaguar 10.2.3.  I'm running the latest versions of the 
iLife apps.

Eagle