Thank you for the quick reply. Sadly it did not work . I can only choose between 44100 and 48000 hz but with both situations, the problem is still there.
It's most like an USB problem I think, it happens wherever I connect the cable (in any of the 4 ports). I think the Mac sends an electric signal (you can listen the speakers or see the leds in the sound card) to all ports while stopping/starting/waking/rebooting. Actually while starting it happens more than one time.
I would send a video, but I don't know why but my "Insert Video" button is unactive..
The problem you describe could happen if the electric outlets are not correctly grounded.
For power, your speakers are plugged into an outlet, right?
Is your Macbook power adapter plugged in to the same oulet? If not, and if it is possible with the power cords you have, try plugging both - the speakers and the macbook power adapter - into the same duplex outlet.