By splitting the cable before the box, you can have the DVR & Tivo record independently of one another, recording up to 3 shows simultaneously, while watching any of the shows or a previously recorded show on either box.What is the advantage of splitting the cable before the cable box? What about just having dual outputs from the cable box, one to the TV for the HDTV channels and then a second one from the cable box to the TiVo and then back to the HDTV for the HD channels
Trying to feed the Tivo from a DVR is highly problematic, impossible really. You'd only be able to record whatever the DVR was outputting at the time; using the UI on the DVR would mess up the recording. You'd be going through a double MPEG encoding cycle also, it would look bad. If you are talking about just the coax RF feed, the RF output on the cable DVRs is often only ch3 modulated output = to its other outputs, same issue. It's usually not just an RF passthrough, except in some cases if the box is off. Splitting is really the only reasonable way to go.