I am using a Yamaha RX-v371 receiver, connected to a motorola RNG 150N cable box (comcast). Using HDMI for the connections.
If I connect the cable box straight to the TV, there's no problem. If I connect it through the receiver, the audio cuts in and out sporadically on many channels.
After some time searching, I tried setting the cable box audio output to L-PCM (default is AUTO) stopped this happening, but if I understand correctly this means I'm now limited to 2 channel (or 2.1), and won't be able to take advantage of anything broadcast in 5.1 surround.
I have two identical cable boxes, and tried switching them, with no improvement. I connected a blu-ray player to the reciever (using hdmi) and was able to watch in 5.1 with no audio dropout. I switched the cable box and blu-ray hdmi ports on the reciver, and the problem followed the cable box. I tried changing the cable too with no luck.
If anyone has any suggestions or can clarify whether I'm correct about PCM being sub-standard to 5.1, I'd really appreciate it.