You should be able to combine the TV2 out with the antenna using a splitter in reverse. In the 722 menu, press 6, 1, 5 to get to the modulator set up and change the TV2 output channel to a channel that isn't nearby any channels from the antenna. The last time I tested the TV2 out from a 722 I think it was around 16dBmV so you shouldn't need an amp unless you're splitting much more than a 2-way and 8-way. There should be a little device called a Diplexer at your home run. There should be a port labeled VHF/UHF or ANT or maybe TV, that is the one that gets combined with the antenna.