Terapin: in case my post left you confused - there is no antenna "analog pass-through" on the Zenith DTT900.
What I did was keep my cable-TV feed connected to the RF input, while connecting my DTT900 and antenna to the component inputs. I toggled back and forth between the cable tuner and the DTT900.
At this time, I probably will keep the Limited Basic Cable TV subscription because it is tied to my high-speed internet service and (due to a multi-product discount) costs me very little. But I can honestly say, the condo unit I live in never had viewable OTA. Doing without cable TV is definitely an option.
As someone who had the RCA DTA800B in my home for five days, I observed that the Zenith has much more stable OTA reception, using the exact same so-so amplified indoor antenna, than the RCA.