Audio with Apple led cinema 24' : not MPD but USB !

[filou2toulouse]

Hy every one
I have a Apple led cinema display 24' and a XFX 5770 graphic card.
I use a DSDT patched by Trauma to enable HDMI audio.
SL 10.6.6
I tried for weeks nows to have sound via my screen (my wife does not like the speakers I had to use
Today, my daughter was playing on the windows session (the audio via screen is working in windows !) and suddenly she removed the minidisplay port ... no more image of course but the audio was still there !!!
I put the MDP cable back and the image was back ... then I removed the USB cable and the sound disappeared!
So the sound for the Apple cinema display is not in the MDP but in the USB port !
That is why I cannot get it via MDP I suppose !
I'm a perfect noob so this point is probably already well known, but if it is not this could help in "injecting" audio for the Apple display users.
If any one have a solution ?
Sorry for my typically french english
By

 

[filou2toulouse]

Hello
I make the question and the answer
The solution is simple : put the USB cable in the primary connector (the yellow one on my MOBO) and not in a secondary one (blake one) and ... miracle, you can choose the audio on screen option and it works !