I've found an USB 3.0 hub that has 12V 5A power adapter. USB 3.0 specification says that ports should support 0.9 A. The hub has 10 ports. Users say that it's very stable and suggest that in order to provide 9A in total the hub converts 12V to 5V with larger current. But is it possible without a transformer? Could they use some small transformer for each of the ports?