richms: Masthead amplifiers are not made for driving many TVs, they have a lower total power output than you need to split many ways, they are made to bring a low level signal up to be able to drive down a cable

You want a distribution amplifier that you put inside and can output over 110dB - most mastheads struggle to get near that without massive distortion which will kill the digital signals and make diagonal lines appear over the analog stuff.

Hence why I recommended the Kingray MDA20U 

an output figure that equals the DW42, 118dB @ -60dB IMR