I am using a cm-7777 with a Denny's HD Stacker antenna at about 40' with a rotor. Without the pre-amp the Buffalo signals arn't strong enough to reach the TV. With the amp the signals are more than strong enough, but the picture breaks up inconsistently. From what I understand, an overpowering channel, with or without a pre-amp can have a negative effect on weaker channels up to 6 in either direction. Thats why I believe that the CHCH tower is causing problems with 7,9,14 and 33,38 and 39 in my setup. I will attempt to contact CHCH and CTS to see what their techs say. Thanks for helping point me it the right direction.