I have three 4 port modulators right now combined with cable. My modulators outputs all go into a modulator combiner and then go into a 2 way combiner along with my cable feed which has a low pass filter on it. Out of the combiner I go to a 3 way splitter which goes to three 1x6 distribution amps. When first installed I had some real problems but installed an attenuator before the modulator signals when to the combiner. I bought the kind you can control with a dial and my picture is now perfect.