As I understand it, TiVos have 2 tuners and require 2 cables.
You may need to replace your 4-output ** with a 5 or 8 output **.
That is all I know about TiVos, and by not owning one yet, all i can say about em.
For all that I know there are versions of TiVos with ony one tuner. XD
If...