I'm still on 2.6.11 kernel... But it seems that the problem comes from the dependencies. Indeed, i've looked forward the alsa-utils package and here is the dependencies i've discovered:
Conflict: udev (<0.060)
And the only udev available in the testing repository is udev 0.056-3... And if i want to uninstall udev, then i've got the same "do you want to remove also gnome, hal, etc... ?" stuff...
So it seems that udev 0.060 should be include soon in the testing repository, but meanwhile we've got to wait without any sound
I'll reply later when everything will be repaired.