Hello, I have five TVs outfitted with Comcast digital boxes and one of them is not receiving all its channels. The fifth TV is furthest away from source (12-15 meters) with a cable length possibly over 50 ft. I highly suspect the missing channels are due to a weak signal. I already have a HDTV amp, but it appears to not provide enough juice. The question is this, can I simply add another amp to raise the db to fix this problem?