I use this powered hub (iPad2 -> cck -> belkin hub to go) It works great. I threw the funny unpowered part in a drawer.   http://www.amazon.com/Belkin-USB-2-0-7-PORT-HUB/dp/B000TTTJ36/ref=sr_1_1?s=electronics&ie=UTF8&qid=1357692692&sr=1-1&keywords=belkin+hub+to+go

Old pc. Are you sure you have a 2.0 USB port? Is there enough bandwidth on USB 1.0?

USB cables only carry zeros and ones no high frequencies for the ferrite to filter out. The high frequencies are on the other side of the odac. So I guess the difference you heard must be for some other reason.

I have been using the ODAC/ O2 with a USB powered hub I had laying around. It works great it is just messy. I don't know if the hub is isolated.

Thanks for the info about the power injector. I was interested in it as a solution for the iPad CCK setup. I wonder if there is any downside to using it with an iPad.