Ah… missed that so I’ll give you a little more info here.
CableTV is the source of this problem in many scenarios like this. The issue is that the cable line is grounded in multiple places including where it enters the home. They typically ground it to a water line or or the outside of the electrical panel, but never to the ground bus inside the panel. Because of this there is a significant difference in ground potential between the shield on the coax cable the the third prong of your electrical outlet. This causes a current to flow (at 60Hz frequency) between the cable ground (shield) and the closest thing that is connected to the ground bus in your electrical panel. The TiVo is ungrounded and the receiver is ungrounded so the next thing in line is the DAC. There’s actually a current flowing between the DAC’s ground and the cable’s ground and it’s riding on top of that single-ended interconnect! That’s where the hum is coming from. Unplugging the DAC from the wall eliminates that path and the current stops.
So… if you disconnect the cable from the TiVo (or the TiVo from the Anthem) and the hum stops then you need to break one side of that ground. I don’t suggest lifting the ground on the DAC as that’s a safety issue, but you can lift the ground on the cable line. Just pickup one of these:
http://www.jensen-transformers.com/product/vrd-1ff/
If you have a coax line into your TV as well then you’ll need one there too.