Ken,
Whilst I have no formal inside knowledge, I would say the chances of B&O ever producing a DVB-C card are zero for many reasons. Connection will have to be via STB controller.
- It has always been its stated policy, it will support DVB-S & DVB-T, but will not support cable.
- There are so many different frequencies used by cable company which do not conform to standards.
- The chances of a positive return on their considerable design development costs are very small.
I notice from your IP address that you are in Colorado and the large cable industry in the US would be a particular challenge as many of these companies have their boxes made to their spec's