What are you using as an audio source? Is this all using audio return channel or some garbage like that? If so, the list of people who complain about ARC is immense. Like, a crazy number of issues are related to the use of ARC.
If you are using an external source for audio, like a cable box hooked up to your Denon, then the cable box creates the audio signal to the Denon, and you should only have video out of the Denon to your TV. If audio drops, but the TV picture stays in place, then that would be very weird and indicate a possible issue with the cable company. If you switch to a different source, like a Blu-ray Disc player, and you don't have any audio issues, then it most likely is the source itself.
We had two cable boxes that both started acting up. It ended up being a problem with our cable provider, not the boxes or cabling.
I will say, that at 12' in length, I highly question the support for 18Gb/s signal path on those HDMI cables. So, there would be no harm in replacing them with something better, but it would be good to know what you are using as a source for the audio first, and how that audio is getting into the AV receiver.
