I was hoping this would be fixed by the new firmware but it wasn't. I also still can't say if the problem is on Tivo's part or Time Warner Cable (TWC).
About a month ago I upgraded to HBO (and other movie channels) but I can't listen to any of them in DD51, I have to switch the Tivo Audio output to PCM otherwise there are intermittent -- but continuing -- audio dropouts. I normally use a HDMI cable to link my Tivo to my Denon receiver but even swapping this for component-video and optical-SPDIF audio doesn't help, i.e., it is not an HDMI handshake issue.
I've actually been having this problem for as long as I've had the Tivo, I just hadn't realized it was specific to encrypted channels. Instead, I only knew of one local channel which exhibited the problem and so I ignored it; I now realize that this one channel is (illegally?) being encrypted, marked as not-copyable. So the common thread seems to be encrypted channels.
Is the problem my cable connection then? I've already had TWC double-check everything and, in fact, the problematic channels are all 'hotter' signals than the non-problematic. The strange thing, I think, is that the audio plays-back fine in PCM. Is that PCM signal separate from the DD5.1 or is it part of the DD5.1? Is there some other way of telling (on an encrypted non-downloadable recording) if the Tivo is recording the DD5.1 cleanly?
Or, any other suggestions? Thank you!