Thank you for your answer. Wouldn't 1.2A be enough for the expected hashrate? I read it needed 750mA for a 3.4MH/s performance.
I then found some USB3.0 Hubs with 1.2A so I wonder if that fits the job.
Yes, if you want the stock performance, 1.2A works fine. One of the great things about USB sticks with adjustable clock speeds is that you can squeeze out even more performance - according to jstefanop, up to 5mh/s. That's why you'd get a high powered hub.