I searched and only found this thread where someone seemed to report the same problem I am experiencing but nobody offered any suggestion as to why it was happening: (not permitted to post link, thread is #257558).
The issue is that my TIVO's output audio level is WAY below my other devices (Comcast box, 2 Replays). I usually have my TV set to volume level 40/100, however to get the identical volume level with TIVO I have to take it up to 80/100. This by itself would not be a problem, however at that level what you hear is mostly "buzz" and little actual volume. So my TIVO is almost unviewable because of this.
I am wondering if anyone has any suggestions? Thanks!