I have 3 CMC Controllers: the CH, AI, and TP. And a HP desktop PC (i7 980x).
Along with my controllers, I ordered an inexpensive powered USB from Amazon: http://www.amazon.com/gp/product/B002MV7L6Q
When I opened the box to the hub, my heart sank. Not because it’s a bad hub, but because the power cord on the power adapter is only about 6 inches long, which meant I would need an extension cord to hook it up. Tonight, out of curiosity, I hooked up the USB hub to an existing USB extension cable behind my monitors that I used to connect the wireless adapter for my Microsoft Wireless keyboard/mouse 5000 combo, and connected the controllers as well.
To my surprise, they powered right up without an additional power supply. Furthermore, they work with Cubase just as well as they did plugged into their own USB ports.
I suspect that on a laptop that’s not plugged in, you might need power… but on a desktop, it doesn’t seem necessary. Your mileage may vary depending on your PC or your number of controllers.