Just because the hub works with the odac does not mean it will work with every other device. It may not be the hub, but the fact tgat it works with the odac doesn't prove anything. In fact, if i'm not mistaken you're saying the c5d works when you're not using the hub. That more likely rules out the c5d as a problem if that were the case.
Not to be a pain, but could you clearly list all of the exact setups in which it doesn't work as well as the setups in which it does work? Maybe we can figure it out? Maybe it is the adapter, but i'd like to go over all the situations if it isn't too much bother...
John might have other clues as well, but he seems to also think it isn't the c5d. However he would test it for you if you want to be sure. But i'm guessing it's the hub or adapter personally..
I had this same problem well before I used this hub. But I will not use the hub this time. In order to simplify this, I am using my iPhone 4S with its 30-pin CCK through the USB cable I have been using with the ODAC for months, out to the C5D instead of the ODAC. I am not using the original USB cable, Lightning CCK, or the iPad. This setup does not work. So all I do is turn the C5D on and off and on and off. Sometimes audio comes through to my headphones, but most of the time it does not and plays from the phone. I have not changed or done a thing during this test other than toggle the power switch. I then substitute the iPhone and its 30-pin CCK with an iPad and its Lightning CCK . I have the same problem that is intermittently solved in the same way, the toggling of the power switch several or more times. I then use the C5D as a DAC/amp for my Mac mini. In this case it works several times in a row. I am listening to it as I write this. The only difference is I am not using either CCKs, but I am using the same USB cable.
So to be clear, it works with the usb cable only to the mac mini and no failures?