Thank you all for your reply.
I spent over 15000 yen for this monitor model just for the prettiness of the integrated speakers so I wanted to use the monitor speaker in priority but I received computer +monitor and if everything work fine , the wire of the integrated speakers went off during the transportation!
DAMN! what a waste, I have now two useless speakers and paid this extra for nothing:(
So I guess I will have to buy new speakers and plug it on the back of my XVI which is the simplest solution.